Why Do Flammable and Inflammable Mean the Same Thing?


English is a trickster of a language, evidenced by the fact that two words that appear to be antonyms can actually mean the exact same thing. For the most part we manage to bumble along without confusing the two, and can figure out which meaning is intended based on context (although in the case of regardless and irregardless some extra time is needed for teeth-gnashing). We know that inhabitable refers to a place that is habitable, and don’t feel any need to stop our conversation to point out the superfluous in- prefix.

However, every once in a while we come across a pair of words that it really would be better to not confuse. A fine example of this is flammable and inflammable.

Looking at similar words, it is clear that such matters could be very simple; after all, combustible means “capable of catching on fire and burning you to death” and incombustible means “this thing is safe to play with matches around” (more or less). Yet flammable and inflammable both mean “able to be set on fire.” Why in the world is this? Do the language gods have a cruel streak?

There is a fairly clear reason for why both these words carry the same meaning: the prefix in- does not always function as a negative prefix. Sometimes (and this is one of those times) it serves as an intensifier. It’s fairly obvious how this could lead to problems.

Surprisingly, both flammable and inflammable coexisted peacefully in English for hundreds of years before anyone decided to do something about it. Inflammable is the older of the two, with recorded use as far back as 1574. Flammable begins to appear in 1655, when Margaret Cavendish described oil as being “hot burning and flamable” in her Philosophical and Physical Opinions. One of the reasons there was little confusion about these words is that flammable was used much less often than inflammable.

But in the 1920s the eagle-eyed language guardians of the National Fire Protection Association (NFPA) realized that many people were viewing the in- in inflammable as a negative prefix, and were at risk of consequently incinerating themselves at a much higher rate than was desirable. The NFPA advocated to have flammable used exclusively for warning labels (such as are found on mattresses, oil cans, and other things that will catch on fire if you put a match to them), and managed to slightly nudge our language toward a more sensible path. Though in the recent past flammable is used more often than inflammable, this pair still incites controversy—and laughter.

Ammon Shea is the author of Bad English: A History of Linguistic Aggravation and Reading the OED: One Man, One Year, 21,730 Pages. He lives in New York City with his wife (a former lexicographer), son (a potential future lexicographer), and two non-lexical dogs.



  1. Sean C -  April 12, 2016 - 2:57 pm

    Flammable means easily ignited and quickly burned. The prefix “in” denotes the negative connotation of the word, thus inflammable means something akin to exploding or catching fire in a bad way.
    A good piece of firewood is flammable. A tank full of gasoline on a boat is inflammable.

    • Don W. -  May 17, 2016 - 6:52 pm

      The root of the word inflammable is inflame – meaning to ignite. The ‘in-” prefix in this case is not a negative.

    • Samuel Othino -  July 31, 2016 - 9:37 am

      You are very right.

      • Pushy -  August 27, 2016 - 11:44 am


  2. Sean -  April 12, 2016 - 2:54 pm

    Flammable means easily ignited and quickly burned. The prefix “in” denotes the negative connotation of the word, thus inflammable means something akin to exploding or catching fire in a bad way (house on fire, as opposed to a good way, fire in the fire pit).

  3. Jeff -  March 4, 2016 - 11:25 pm

    Someone told me to be credulity and cool in a sentence. When I questioned him about it he said auto correct changed his word to credulity. My understanding of the meaning of the word is no where close to what he said he meant which was safe, we were talking about New Years eve and plans. I did not push any further. Does anyone have any idea of what word could have been corrected that meant credulity for safe or careful?

  4. Ann Nonymous -  February 24, 2016 - 4:09 am

    Inflammable, inhabitable, invaluable. What others words such as these?

    • Bob -  November 3, 2016 - 6:53 am


  5. Anonymouse -  February 12, 2016 - 7:18 pm

    IN flammable
    The ability to be IN flame(s).
    It’s like inhabitable, the ability to be support life in an area.
    Flammable comes much later, so it’s meaning is probably all mucked up.

  6. Ray Thomson -  February 10, 2016 - 4:29 am

    Just stop thinking of ‘in’, in this instance, as a prefix.

    You may have an inflamed urethra. However excruciating this condition, it would appear from some comments not to hold a candle to figuring out the non-existent difference between flammable and inflammable.

    Sufferers may take a crumb of comfort from knowing that no matter how inflamed the urethra, it is unlikely to burst into flames.

    On the other hand, of course, language teaches us that there’s always the exception that proves the rule.

  7. Aaron F -  February 9, 2016 - 6:51 pm

    If someone becomes “inflamed”, it doesn’t mean that they’re cooling down. Inflammable simply means “able to become inflamed”. Inflammable as the negative of flammable is a colloquialism perpetuated through force of collective habit. It’s not an issue to become inflamed over. Let’s please stop throwing around inflammatory comments and biting each other’s heads off.

    • Niger Nurah -  February 16, 2016 - 1:42 pm

      Good One Aaron F. !
      I’m still ling ol !

  8. Pero -  February 9, 2016 - 6:27 am

    Am almost getting sick and tired of these words with same meanings

  9. Tim Baker -  February 9, 2016 - 6:02 am

    I think that a lot of confusion results not from the way the word begins but the way it ends.

    FlammABLE — ABLE to be set on fire (seems to make sense)

    If Inflammable indicates not just ability but more likelihood then maybe changing the ending of the word would clarify better.

    Inflameous (Dangerous) perhaps?

    I can’t think of any other possibilities right now – anyone else?

    • Niger Nurah -  February 16, 2016 - 1:55 pm

      Naw, Aaron hit it on the head. To inflame. Is it able to become inflamed ? If so, it’s inflame able – inflammable. A flame. Does it have the capacity to become a flame ? If so, it’s flammable. Same difference. (to use another potentially confusing phrase)

      You’ve gotta love words to be able to catch on to some of this stuff. I had to EARN any A in math I received in school. In English ? I’d just idle up beside any A I wanted, and it’d follow, mesmerized. lqtm (lqtm is my new invention. Lol ain’t appropriate in most cases. L aughing Q uietly T o M yself is more befitting)

      …got too much time on my hands tonite / tonight.
      Bye y’all !

  10. Anonymoose -  January 25, 2016 - 7:30 am

    Someone has probably already said this, but what if inflammable is related to both the words in and flammable? Just a thought.

    • hey -  February 9, 2016 - 2:03 am

      be quiet

      • Niger Nurah -  February 16, 2016 - 2:11 pm

        Why be quiet ? How ’bout you just stop reading ?

  11. Harpo -  January 12, 2016 - 9:38 am

    In the timeless words of Woody Boyd, “Boy, I sure learned that the hard way…”

    • Seth -  February 7, 2016 - 9:17 am

      Haha, I love Cheers! Such a great show.

  12. Roy R. Simmons -  January 11, 2016 - 1:27 pm

    it sames to me that there is a better way tosolve this problem. Do away with the letters in completely. Use the word famable as it is intended meaning it will burn. Use the most meaning (UNfamable) meaning will not burn. End of problem. thank you R.R.Simmons

    • Tony -  February 4, 2016 - 5:36 am

      So you want everybody to alter their pronunciation as well as their preferred use?

    • Niger Nurah -  February 16, 2016 - 1:59 pm

      That would mean completely changing an entire rule of English ! Nope – not rational.

  13. Porno McFriday -  December 23, 2015 - 6:21 pm

    Flammable = able to catch fire
    Inflammable = high likelyhood of catching fire

    • Jeff -  January 10, 2016 - 11:18 pm

      Inflammable: intensely flammable?

  14. George -  December 21, 2015 - 2:13 pm

    Interestingly, the French use ininflammable to mean non-flammable.

    • Guillaume -  January 16, 2016 - 8:46 am

      But we do not use it (I think so…). I think we are more likely to say ” is not inflammable”, or some other word such as “ignifugé”.

    • Niger Nurah -  February 16, 2016 - 2:02 pm

      Ininflammable ? That makes sense. Not able to be inflamed.

  15. Robert -  December 20, 2015 - 2:28 am

    I find this to be a rather incendiary topic :)

  16. Haylee -  December 10, 2015 - 12:07 pm

    I hadn’t thought about this one before, but it is rather scary how easy it is to confuse the two. There are also plenty of other examples of “in” words that aren’t eliminators if you stop to think about it long enough.

    Invaluable = exceptionally valuable

    Infamous = exceptionally famous (with a bad reputation)

    Inflammable = exceptionally flammable

    Please, please don’t misread this word!

    • Cephas -  January 3, 2016 - 11:23 pm

      I think you have a point there Haylee.

    • Niger Nurah -  February 16, 2016 - 2:04 pm

      Yeah, but it’s different in the case of the word inflammable. Refer back ⬆️ To Aaron F’s input.

  17. Pier -  November 23, 2015 - 5:16 pm

    In my opinion, if the author of the article would have gone a little more back in time with the etymology, without limiting to 1574, the explanation would have left less doubts.
    Consider the latin original: in+flamma (flame): that does activate a flame. In this case the particle “in” means to activate, to give the sense of direction towards something…
    In Italian, still, just infiammabile exist, no flammable or similar exist.
    The prefix “anti-” is used to compose the negative form.

    Anyway, easy to also to understand that since 500 years in English a form without “in” has been used and this create some confusion…

    Just keep in mind that “in” is often not negative :)

    • Mike -  November 24, 2015 - 9:28 am

      Absolutely. I will hazard a guess and say that “inflammable” comes from French (it is the same word in French), while “flammable” was invented by the same kind of people who say “I could care less” today. And five hundred years from now, people will have similar discussions about the nonsense that is invented these days because that will have become the norm.

      • rob -  November 28, 2015 - 10:36 am

        Except that in this case, it makes a lot of sense to make the change. Even below in the comments, people who have read this very article, are confused. And confusion over this can have consequences.

        • Peter uche -  February 9, 2016 - 6:15 am

          Its just like COMPLETELY AND FINISH

          • Niger Nurah -  February 16, 2016 - 2:07 pm

            ABSOLUTELY NOT like completely and finish ! One is an adjective (completely) used to DESCRIBE. The other is a verb, used to communicate an ACTION !

  18. William Bryant -  November 19, 2015 - 11:59 am

    Why do the words terminate and EXterminate mean the same thing?

    • Nick -  December 14, 2015 - 9:28 am

      The use of those words are completely different. In computer speak, you can terminate a running program, you can not exterminate it. I cant think of any situation where terminate and exterminate could be used interchangeably and have the same meaning.

      • Well of Course -  December 28, 2015 - 4:50 pm

        “I terminated that wasp by stepping on it.”

        “I exterminated that wasp by stepping on it.”

        • another opinion -  January 10, 2016 - 4:37 pm

          “I terminated that wasp by stepping on it.”
          This is incorrect use, probably stemming from the use of ‘termination’ as slang for killing in films. What was terminated is the lifespan of the wasp, not the wasp as a creature.

          “I exterminated that wasp by stepping on it.”
          This on the other hand actually means killing something – although usually taken to mean leading to extinction, so exterminating should be used only when killing a species or group, whether within a smaller or larger eco system. Eg. extermitaing vermin within a micro eco system, such as a house or garden. You might exterminate mice in an infested house, but you would simply kill a single mouse, not exterminate it. Well, unless you are a Dalek that is.

          • Guillaume -  January 16, 2016 - 8:52 am

            I agree. The use of terminate is rather recent and it think it is used to mimick a machine like “train of thought”. Terminator terminated many things for instance.

        • Niger Nurah -  February 16, 2016 - 2:10 pm

          A term. To end the term of a thing. Very good one, @Well Of Course !

    • Muscle Chaser -  January 12, 2016 - 1:29 am

      Not really… Terminate means to end, Exterminate means to get rid of.

  19. shona -  November 15, 2015 - 9:09 am

    Flammable means may ignite. Inflammable means has been designed NOT to ignite.

    • Peter -  November 18, 2015 - 2:12 am

      Except that is not true. Inflammable and flammable both means easily ignitable

      • William Herndon -  November 21, 2015 - 9:47 pm

        Thank you. I am a fire preventionC OF :(G-23) EXPIRATION DATE:
        inspector FDNY. The English language has exceptions to the rules of ” prefix (in..) inflammable does not mean “not flammable “. The material is flammable it can catch fire easily. Thank you for clarifying that the use of “in-” prefix is an exception to the rules used in English language in the case.

      • angelj -  November 23, 2015 - 10:57 am

        how that not true ?

        • shttlker -  December 8, 2015 - 3:50 pm

          what is day it.

          • gjon -  December 15, 2015 - 5:34 pm

            the day tuesday i think it is

    • TheoDusko -  November 26, 2015 - 12:49 am

      Did you not read the article? Or even the title? Both words mean that the material can catch fire. If you attempt to create a nonflammable material and fail, there is no special word attributed to your material. It’s would be considered flammable or inflammable. Same thing. Similarly they don’t have a special word for a material “designed” not to be toxic but still is. It’s just toxic. Don’t eat it. On top of all this, seeing as how the ‘in’ prefix can be used as an intensifier, inflammable means, if anything, that the material is MORE likely to ignite. So if your so called nonflammable creation turns out to be inflammable, you have failed HARD.

    • Niger Nurah -  February 16, 2016 - 2:11 pm

      Wrong Shona.

  20. Peter Riley -  November 12, 2015 - 11:48 pm

    It’s quite simple. “Flammable” means catches fire, “Inflammable” means it doesn’t. As an OHS manager I’ve known and lived with this for over 30 years. Duh!

    • Peter -  November 18, 2015 - 2:11 am

      Except for 30 years you have been wrong then. They BOTH mean catches fire easily.

      • Shaun Kelly -  December 4, 2015 - 4:42 pm

        Thank you!

    • Rylan -  December 6, 2015 - 1:06 pm

      it depends on the origin of the root. the stem in latin does not always mean not. in other languages, it can mean not, but not always. like almost any language other than English (although sometimes English) words (and stems) can have more than one meaning. hope I cleared some things up.

      • Rylan -  December 6, 2015 - 1:15 pm

        there is also the difference between the prefix in- and the prefix im-, though I haven’t quite figured that one out yet though

        • I dunno -  June 15, 2016 - 4:13 am

          im- is used when the next word starts with ‘p’ or ‘m’. I don’t think that there’s a difference.

          • I dunno -  June 15, 2016 - 4:17 am

            And also ‘b’.

    • Ken -  December 11, 2015 - 7:20 am

      But sir, your remarks are inflammatory.

      • Nick -  December 14, 2015 - 9:33 am

        I nominate Ken for one of the best comments ever. I never thought I would laugh out loud reading dictionary.com comments.

        • Eden -  January 14, 2016 - 10:07 am

          I’m with you, Nick. I laughed so hard I was crying! The wood you put in the fireplace is FLAMMABLE (but only just) and requires a bit of effort to ignite. But that kerosene-soaked rag better not get too close to the heat or it will demonstrate with startling efficiency what HIGHLY INFLAMMABLE means!

  21. hi -  November 11, 2015 - 7:22 am

    i can’t watch simians yet so it docent help me as much as other,

  22. john -  October 22, 2015 - 6:46 am

    i am vary confused

  23. toughghost101 -  October 16, 2015 - 11:15 am


    • Daylond -  October 20, 2015 - 6:34 pm

      Me too

    • GadgetGabe -  November 4, 2015 - 9:52 am

      It really can’t get any simpler.

      • jess -  November 16, 2015 - 6:39 am

        ok gadget gabe, please explain. thanks.

        • Peter -  November 18, 2015 - 2:13 am

          They are the same

  24. pollygone -  October 7, 2015 - 8:15 am

    Nobody has a problem with properly understanding inflame, inflamed, inflamation or inflammatory – or do most people think inflammatory means something similar to conciliatory? And why do things not simply “catch fire” but “catch on fire”?

    • anti -  October 11, 2015 - 5:43 am

      “Catch fire” is used commonly in some places. It can refer to creating fire as well as something being on fire. My father and his family who are from Jamaica tells stories of needing to warm a room (or start a fire) and someone would go and “catch fire” (create a fire). I also recall that when I was a child if I stood too close to the stove he would say “don’t let your close catch fire”. However, growing up in Maryland I can’t recall hearing “catch fire” used by people outside my family to refer to starting a fire.

      • Jason -  October 13, 2015 - 2:02 pm


        • awesomesauce -  October 21, 2015 - 7:17 am

          this site is wird and freind me on roblox

          • Aluhu Akbar -  November 19, 2015 - 3:32 pm

            Dude seriously.
            No spam.
            Its bad for you

            Pun intended

          • bbbbbbbbbbb -  February 2, 2016 - 4:57 pm

            SPAM IN A KAN

        • Aluhu Akbar -  November 19, 2015 - 3:28 pm

          Well Jason i like that you can spell clothes

          ALUHU AKBAR >:(

          • Aluhu Akbar is an Asshole -  December 21, 2015 - 1:57 am


      • Ruth Howlett -  October 17, 2015 - 6:04 am

        My family used to say, “Don let your clothes catch on fire”. Go figure.

    • Ron -  October 11, 2015 - 9:24 am

      I wonder what kind of glove you need to catch fire. Can I use my Rawlings? I suppose it depends on the size of the fire, although a mass of flaming liquid flying at you would be difficult to capture in a catchers mitt. Too splashy.

      • Deb O' -  November 8, 2015 - 9:36 am

        you could probably use either a flammable or inflammable glove to catch fire.

        • Anonymous -  December 3, 2015 - 7:54 pm


        • Sarah -  January 12, 2016 - 1:37 am

          Best answer/quick retort Ive ever seen. I award you 5 points senor!

  25. ahlam -  September 11, 2015 - 1:58 pm


    • Jordan -  October 6, 2015 - 9:13 am

      Flammable and Inflammable mean the same thing because think of Minecraft, when you try to light water on fire it lights on fire for a second but then goes out again. It is still flammable.

  26. Dana -  September 10, 2015 - 10:58 am

    What about the words unravel and ravel? They both mean the same thing, even though “un-” is almost always a negative.

    • Ron -  October 11, 2015 - 9:34 am

      That’s interesting. Until I read that comment, I had no idea that as a verb, ravel means to de-tangle. I always used it as a noun, which means a cluster, like ravel up the yarn. or the extension cord or something. Jeez, what a complex word.It’s a wonder anyone can learn english without going clinically insane.

      • Mackie -  November 18, 2015 - 3:37 pm

        How about: you & ewe; rain, reign & rein; so & sew; hail & hale; your, yore & you’re. Or: wise man and wise crack = different. Personally, I have always used ravel and unravel to mean the same: come apart, usually referring to string, thread, yarn, a piece of cloth. English is fun!

  27. Francesca -  September 9, 2015 - 7:39 pm

    Why does the English language have to be so confusing?! I mean, seriously, whoever created the English language is smart, sure, but really? REALLY?! Do we have to have two different words with the same meaning?
    Oh by the way orange rhymes with sporange. And borange. If you don’t believe me, search it up.

    • Noori Thompson -  October 7, 2015 - 5:23 pm

      Also, orange rhymes with Blorenge, a hill in Wales.

      • Aluhu Akbar -  November 19, 2015 - 3:30 pm

        No Way ha! anyone who says that nothing rhymes with orange is wrong! I was right!

      • Hope -  December 9, 2015 - 1:37 am

        I like fish, that rhymes with Slemish, a mountain in NI. Not just a hill a MOUNTAIN.

    • Monica -  October 15, 2015 - 2:46 am

      Haha. That english langauge creator guy. What a meany. That one person. Can’t believe he did this to us

      • Tony Maddock -  October 26, 2015 - 3:02 pm

        At least he didn’t lumber us with the totally meaningless and unnecessary complication, common to most other languages, of allocating a masculine or feminine gender to every noun. And this can vary between languages, an example being the word for ‘bill’ (as in ‘may I have the bill please’) which in Italian is masculine (il conto) but in Spanish is feminine (la cuenta). Crazy or what?!

        • fred -  October 27, 2015 - 3:47 pm

          And what about el tigre and la tigre? Not even -o or -a endings to help!

          • K220 -  November 9, 2015 - 12:22 pm

            And German has feminine, masculine and neuter!!!

          • Srta. Voleta -  November 10, 2015 - 8:54 am

            El tigre (m).
            La tigresa (f).


      • Mr Fida Ali Engr -  December 5, 2015 - 7:39 am

        English language is a lovely and interesting language. It has a lot of fun for learners that keeps its speakers aware of its delicacies. Flammable and inflammable are a pair of words which is synonym i.e. capable of producing flames of sufficient intensity on ignition. On the other hand this pair creates a little confusion also for learners. Never mind, these two words have the same meaning.

    • Ned -  November 3, 2015 - 4:28 am

      I know! I didn’t know about borange but I knew about sporange!

  28. James -  August 18, 2015 - 6:38 pm

    I’m surprised no one has yet pointed out that the root word for flammable is flame, whilst the root word for inflammable is inflame. One is a noun and on is a verb, but this is why they both mean the same thing.

    • Chris -  August 20, 2015 - 10:01 am

      Right. To add to that, there is a difference in use. E.g. “Their inflammable passion” is fine, but “their flammable passion” doesn’t make sense (unless read poetically).

      • Philip -  September 6, 2015 - 9:21 am

        What a wonderful example.
        Thank you.

      • EggyRepublic -  September 6, 2015 - 12:02 pm

        this is why I like chinese

        • hello -  October 14, 2015 - 11:06 am

          me too

        • Nathanael -  October 15, 2015 - 11:35 am

          What the what why do you like chinse

          • K220 -  November 9, 2015 - 12:22 pm

            I prefer Indian – it’s gorgeous!

          • tj -  November 16, 2015 - 11:29 am


          • Aluhu Akbar -  November 19, 2015 - 3:31 pm

            Because there food is amazing

    • ANTHONY -  September 8, 2015 - 11:12 am


    • Mr. S -  September 11, 2015 - 5:20 am

      None of them are verbs.

      • Jim -  October 4, 2015 - 8:59 pm

        LOL Quite an ironically inhumorous statement. Ironically being based on the noun IRON.

        ironically DEF: To vigorously iron a statement

        And then INHUMOROUS being based on the adverb INHUMAN…..right?

        inhuman DEF: the act of being in a human such as a surgeon does when positive financial stimulus is administered.



        • Japanophile -  November 9, 2015 - 3:51 am

          Irony is the opposite of wrinkly. Apparently.

    • William Herndon -  November 21, 2015 - 9:54 pm

      Thanks I will not confuse that again.

    • TimO -  December 1, 2015 - 5:49 am

      WELL DONE James***…. inflammable is indeed derived from ‘to inflame’ as in “bring to the condition of fire’; hence inflammation = suffering from having been brought to the condition of fire and inflammable is ‘capable of being brought to the condition of fire’ and inflammatory is ‘a situation which leads to condition of being brought to fire’ etc.

      Pity I only stumbled across this discussion in December. The ‘confusion’ spoken about earlier, in so many English words does not stem from a “Mr/Dr English” who ‘created’ it but more likely because of the scattered English “committee” who added bits and pieces from different sources over a period of time -its still goig on now, in all ‘living languages’. You note many words in ‘modern’ English have Latin roots, while another lot have (ancient) Greek roots and others have Old English roots and other languages to boot. Thus the rules governing a particular word depend on its root and when two roots from different sources are similarly spelt, their meanings may be quite different in their original language and so in their English usage. (Did you ever wonder about that annoying “I”? Why should it be a capital? To make typing and ‘texting’ more annoying????) Cheers

  29. Scroto T. -  August 18, 2015 - 1:44 pm

    This comment thread is a hangout for the grammar police.

    • jerryg -  September 6, 2015 - 8:28 am

      Of course it is. What did you expect?

      Maybe you’d prefer the Kardashians. Move on.

      • shaun hancock -  September 10, 2015 - 10:52 am

        no it s not

        • Addrehman -  November 14, 2015 - 8:09 am

          yes it’s

    • Wrinkled Scrotum -  November 19, 2015 - 3:34 pm

      It is

    • Nick -  December 14, 2015 - 9:59 am

      I expect grammar police on ESPN’s comment section, but not on dictionary.com’s. What a crazy place to see correct spelling and grammar.

  30. Azzard -  August 18, 2015 - 12:19 pm

    In the 1950′s, 1960′s and perhaps beyond, at least in some locations in Massachusetts, just to add to the confusion, one often saw the “word” “non-inflammable” on fuel oil delivery trucks and the like. That “usage” was truly sufficient to “send one over the edge…”

  31. Val -  August 17, 2015 - 2:44 pm

    How about the word outflammable? If there is inflammable, there should be outflammable too. No ?

    • Neville -  August 20, 2015 - 4:03 am


    • hello -  October 14, 2015 - 11:07 am

      of course not

      • K220 -  November 9, 2015 - 12:23 pm

        Now that is just crazy…but good try :)

  32. Satish Shirali -  August 17, 2015 - 6:54 am

    Candescent and Incandescent also mean the same thing.

    • hello -  October 14, 2015 - 11:07 am

      really? I didn’t know there was “candescent”

  33. James -  August 16, 2015 - 6:20 pm

    I like scrabble…all day long.

    • K220 -  November 9, 2015 - 12:24 pm

      Scrabble – the worst game that was EVER invented! :)

  34. Uruan Inyang -  August 16, 2015 - 2:48 pm

    I`d rather a future revision leaves flammable to combustible individuals while inflammable should describe volatile objects, markets, countries, regions, their politics and/or religions.

  35. Chip -  August 16, 2015 - 1:49 pm

    “Surprisingly, both flammable and inflammable coexisted peacefully”
    The word ‘both’ is redundant in this situation. Were there not 2 there would be no coexistence.

  36. Billy -  August 15, 2015 - 2:21 am

    Michael’s explanation is likable but not authoritative.
    An electric fire can cause things to burst into flames – flammable?
    Petrol, given ignition can just itself burst into flames – inflammable?

    No an electric fire is not flammable, is it?

    • Billy -  August 15, 2015 - 2:34 am

      Another thought…. I have never considered custard as either flammable or inflammable (or even imflammable) and the packet in my kitchen is not labeled either way, I cannot think of anything that cannot be destroyed by fire, even bricks and steel (rocks in a volcano?) so when would anyone say something is not flammable?

      • Billy -  August 15, 2015 - 2:46 am

        Okay, water.

        • Josh -  August 17, 2015 - 6:30 pm

          correction, i should say if it doesn’t react with carbon and hydrogen.

          • Tym -  September 5, 2015 - 2:54 pm

            What gets me in all this is the usage of HIGHLY on notices. Not only do we have flammable and inflammable, but we also have HIGHLY variants of both. It’s flammable meaning it’s something that will burst into flames. That other thing is HIGHLY flammable,meaning it will REALLY burst into flames… superfluous English? (and before you ask… I’m from England – the home of the English language…)

        • light my fire -  August 18, 2015 - 1:40 am

          and fire, of course…….. :-)

        • Bob -  August 19, 2015 - 8:17 am

          If electricity travels through water, the water will decompose into hydrogen and oxygen, both flammable.

          • John Skuz -  August 19, 2015 - 11:00 am

            Oxygen is not flammable but certainly makes a great accelerant.

          • TimO -  December 1, 2015 - 6:07 am

            Sorry Bob, oxygen is neither ‘flammable’ nor inflammable’. Flammable things can combust/burn with flames, for instance sulphur, wood, kerosene, petrol, hydrogen etc (these are listed in increasingly easy to set ‘a-flame’ order, hence hydrogen is very ‘Highly flammable’ whereas sulphur and wood are only ‘flammable’. BUT, combustion refers to a “fuel”or substance chemically reacting WITH oxygen fast enough to have flames. (Rusting is a slower form of combining with oxygen). Oxygen does not combust/burn on its own. It DOES however enable ‘fiercer’ combustion when highly concentrated around a fuel whose temperature is raised to it’s individual ‘ignition’ temperature. P.S. oxygen concentration in normal air is around 21%, limiting the speed of any combustion say in a petrol engine; turbo mode rams more air in more quickly increasing the amount of oxygen available for increased combustion/engine power….

      • Kathy Brown -  September 6, 2015 - 8:09 am

        My husband. : (

        • kia -  November 16, 2015 - 4:33 pm

          i sry for ur loss. make out?

          • Wrinkled Scrotum -  November 19, 2015 - 3:35 pm

            Make out with a wrinkled scrotum

  37. Fariba mobasheri -  August 14, 2015 - 3:39 pm

    Please let me know may it be possible that the word was ‘enflammable’ ,and during time or due to some events it has been changed ? ? ?

  38. Mary -  August 14, 2015 - 3:17 pm

    In reference to a phrase in the last line: “this pair incites controversy,”
    I would say “this pair ignites controversy.”

    This article was interesting, and I appreciate the clarification.

  39. hgviguygu -  August 14, 2015 - 8:10 am

    the word imflammable with an m not an n in every technical reference ive seen and they mean the same thing in America but not the rest of the world

  40. Lisa -  August 14, 2015 - 7:25 am

    I’m surprised no one has mentioned regardless and irregardless! They also mean the same thing from what I understand.

    • James -  August 18, 2015 - 6:34 pm

      Actually, irregardless was not a word until Oxford recently decided to add simply because so many people use it when they really mean regardless. Just like conversating is not a word (should be conversing), or notating (should be noting).

      • Kathy Brown -  September 6, 2015 - 8:13 am

        But “notation” is a word – noun, not a verb.

        • jk -  October 16, 2015 - 6:16 pm


      • hello -  October 14, 2015 - 11:09 am

        pay attention, peeps!

    • Captain Obvious -  September 5, 2015 - 12:20 am

      The article itself mentioned it in the first paragraph.

  41. Michelle The Nerd (MTN) -  August 13, 2015 - 2:34 pm

    by the way, the connotation of the words are both infavorable oops typo XD

  42. Michelle The Nerd (MTN) -  August 13, 2015 - 2:31 pm

    in means into, so inflammable means able to burst into flame, which has the same definition as flammable, just with a small extension (i.e credulous means able to believe, subsequently incredulous means able to believe in). I hope u find this helpful, I study english a lot just in case u were wondering why i called myself a nerd. :p

    • Vern R -  August 20, 2015 - 6:00 am

      Michelle, credulous means believable; incredulous means not believable.

      • pollygone -  October 7, 2015 - 8:08 am

        Neither of you is right about credulous/incredulous. Perhaps you should check the dictionary before you spout such nonsense.

  43. Ivan -  August 13, 2015 - 8:37 am

    I live in Mexico and we to have both words.
    Here we use them to differentiate between what would cause a fire.

    Flammable = Requires flame to start the fire
    Inflammable = Does not require flame to star a fire, requires just a spark to start a fire.

    Inflammable is often used only for chemicals, i.e. gasoline and LP Gas.

    • Dane Tanner -  August 18, 2015 - 5:31 pm

      Thanks for your post.
      As the history of these words have shown that ‘inflame’ and ‘inflammable’ are the root words, and that ‘flammable’ is a non-word made by people misconstruing the ‘in’ as a prefix meaning ‘not’, instead of what it really means: which is ‘into’.
      If we have to use both words, I think your perceived definition works very well.

  44. Moris Agaba -  August 13, 2015 - 2:41 am

    all along I though flammable was an object or substance you could leave around fire and nothing outrageous happened.

    Inflammable I reasoned was a thing or substance that you could not get close enough to open flame without yourself getting a dose of the inferno.

    but now I thing the opposite is the case, but to be safe I will take it that flammable and inflammable mean the some think. FIRE

  45. Ariana Grande -  August 12, 2015 - 5:27 pm

    Flammable and nonflammable are not the same. Flammable is when it can easily be lighted up in flames and non-flammable is when it cannot be lighted up in flames.

    • WDuncan -  August 19, 2015 - 6:38 am

      they are talking about flammable an in/imflammable.
      not nonflammable!!!!!!!!!!!!!!

  46. pay -  August 11, 2015 - 10:49 am

    the root word flammable means fire and in means the same form as so the same form as fire. so that’s my reason why flammable and inflammable means the same thing

    • m -  August 14, 2015 - 8:22 pm

      why then do combustible and incombustible not mean the same thing?

      • Carson -  August 18, 2015 - 6:58 am

        Ooooh, Burn!


        • nooooooooo -  October 13, 2015 - 11:10 am

          ah got em

  47. Liza -  August 10, 2015 - 9:30 pm

    Thanks for the clarification. It is safer to use ‘non-flammable’ rather than using the prefix ‘in’ to avoid confusion.

    • Kent -  August 12, 2015 - 9:25 pm

      I don’t think you read the article? Inflammable in no sense whatsoever means non-flammable. So it would not be correct to say that it is ‘safer to use’ one form over the other. They are two completely opposite meanings.

      • Lynrod -  August 18, 2015 - 3:51 pm

        Flammable is a root word.Non is a prefex meaning not So non-flammable should mean not flammable.

    • joosangbai -  August 14, 2015 - 3:32 am

      YES, YES, YES!

      except anti INFLAMMATORY drug

      • qwerty -  September 11, 2015 - 12:47 am

        For those of you who don’t know what an anti-inflammatory drug is, it is a drug that reduces or prevents internal swelling

    • Marius Serbaneci -  August 15, 2015 - 4:11 am

      or may be “fire-proof” / “fire-resistant”?

    • William -  August 16, 2015 - 8:14 am

      this is precisely the reason for the article, as there shouldn’t be any confusion since inflammable and flammable mean the same thing.

  48. Jonathan Kaplan -  August 4, 2015 - 11:24 am

    What is the desired risk rating for self-incineration?

    • A person -  August 6, 2015 - 8:02 am

      100% :)

      • qwerty -  September 11, 2015 - 12:49 am

        not funny, you have a terrible sense of humour

    • mw -  August 13, 2015 - 11:34 pm

      or did you mean self-immolation :-)

  49. Fayomi Yinusa A. -  August 3, 2015 - 11:37 pm


  50. Fayomi Yinusa A. -  August 3, 2015 - 11:35 pm

    I was happy to find a lasting solution to a long years problem. Thanks!

  51. Gary Hart -  August 3, 2015 - 6:10 pm

    Thank you for your etymological explanation. George Carlin did a fabulous sketch on all three: flammable, inflammable and non-inflammable.

  52. joe -  August 2, 2015 - 1:37 pm

    I always think of Riviera’s moment on the Simpsons when talking about these 2 words.

  53. Thekkedathu Kochaipa Thomas -  August 2, 2015 - 9:07 am

    Being a student of English (language and literature) I feel the explanation given was satisfactory. Even then we need to explore the derivatives of words as well as its etymology. It is during the time of Sir Francis Bacon around 16c. and reign of Elizabeth II Regina that English developed from that of its first poet Geoffrey Chaucer (1350) the Canterbury Tales. Then Dr. Samuel Johnson the first lexicographer (1750) wrote his dictionary in his own whimsical way: Cricket: A game of f..ls, played by two and watched by many. I will further check, explore and revert. Thanks for the present.

    • Michelle The Nerd (MTN) -  August 13, 2015 - 2:27 pm


    • Ken Agutter -  October 4, 2015 - 10:57 pm

      I know our Queen, Elizabeth II has very recently become the longest reigning monarch ever, but I didn’t realise she had been around that long. And who was the impostor Elizabeth I?

  54. Wayne R -  August 2, 2015 - 5:57 am

    This is one of those grammar confusions that has always bothered me. I was happy to see the Simpsons make fun of it and I personally use flammable or combustible.

    • Michael -  August 11, 2015 - 7:31 am

      ‘in-’ (or ‘im-’ depending on the consonant which follows) can be the negative English (and other European languages) inherited from Latin. The prefix ‘in-’ can also come from the preposition, the longer form of which is ‘into’ in English. Thus, ‘habitable’ means “able to live”, subsequently ‘inhabitable’ means “able to live IN”. By extension, ‘flammable’ signifies “able to be burn/flame. Then, ‘inflammable’ can therefore be translated literally “able to burst INTO flame”.

      • Michael L. -  August 13, 2015 - 11:39 pm

        I think you essentially got it right but you need to push the rationale a little further: It starts with the word “flame”, which gives the verb “to inflamme” and then “inflammable” (able to inflamme), So “inflammable” is “correct”. “Flammable” must have come later because of the wrong notion that “inflamme” has the negative “in-”, which it does not. “Flammable” could have been “correct” if the verb “to flame” (or “to flamme”) existed, but it doesn’t, or rather does not with this meaning (I believe…).

      • Brian -  May 4, 2016 - 1:35 pm

        Inhabitable is actually a misleading example to begin with. The word being modified is “inhabit” which is NOT the word “habit” with the prefix “in” – it is it’s own root word in the English language. There’s no root word “habit” which refers to a home or location – you’d have to use habitat, which we can’t use as an example because we don’t have a word “inhabitatable”. On the other hand, Inflammable is the word “flame” with the prefix “in” and the suffix “able”. They’re not comparable.


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