serious

[seer-ee-uhs]

adjective

1. of, showing, or characterized by deep thought.

2. of grave or somber disposition, character, or manner.

   a serious occasion; a serious man.

   Synonyms: staid, sedate, sober

3. being in earnest; sincere; not trifling.

   His interest was serious.

   Antonyms: trifling, frivolous

4. requiring thought, concentration, or application.

   serious reading; a serious task.

5. weighty or important.

   a serious book; Marriage is a serious matter.

   Synonyms: grave, momentous
   Antonyms: trivial

6. giving cause for apprehension; critical.

   The plan has one serious flaw.

7. Medicine/Medical.,  (of a patient's condition) having unstable or otherwise abnormal vital signs and other unfavorable indicators, as loss of appetite and poor mobility: patient is acutely ill.

noun

1. that which is of importance, grave, critical, or somber.

   You have to learn to separate the serious from the frivolous.

serious

/ ˈsɪərɪəs /

adjective

1. grave in nature or disposition; thoughtful

   a serious person

2. marked by deep feeling; in earnest; sincere

   is he serious or joking?

3. concerned with important matters

   a serious conversation

4. requiring effort or concentration

   a serious book

5. giving rise to fear or anxiety; critical

   a serious illness

6. informal,  worthy of regard because of substantial quantity or quality

   serious money

   serious wine

7. informal,  extreme or remarkable

   a serious haircut

Other Word Forms

• seriousness noun
• half-serious adjective
• half-seriously adverb
• nonserious adjective
• nonseriously adverb
• overserious adjective
• overseriously adverb
• quasi-serious adjective
• quasi-seriously adverb
• superserious adjective
• superseriously adverb
• ultraserious adjective
• ultraseriously adverb
• unserious adjective
• unseriously adverb

Word History and Origins

Origin of serious¹

First recorded in 1400–50; late Middle English, from Middle French serieux and Latin sērius “grave, earnest” or Late Latin sēriōsus; -ous, -ose ¹

Word History and Origins

Origin of serious¹

C15: from Late Latin sēriōsus, from Latin sērius; probably related to Old English swǣr gloomy, Gothic swers esteemed

Synonym Study

See earnest ¹.

Example Sentences

However, we suspect it actually contains spice, a more potent drug that is highly addictive and can cause serious side effects.

From BBC

According to Roberts, the team is hopeful Glasnow’s issue is not serious.

From Los Angeles Times

A public admonishment is typically issued for serious misconduct.

From Los Angeles Times

"It is clear there is a serious issue in the Australian sunscreen industry that urgently needs to be addressed," said Rosie Thomas, the director of campaigns, in a statement to the BBC.

From BBC

He pledged "serious" cuts to the benefits bill and made the bold claim that he could "stop the boats within two weeks".

From BBC

Related Words

• dangerous 
• deep 
• difficult 
• far-reaching 
• grievous 
• important 
• major 
• meaningful 
• severe 
• significant 
• tough 
• urgent