litmus

[lit-muhs]

noun

1. a blue coloring matter obtained from certain lichens, especially Roccella tinctoria. In alkaline solution litmus turns blue, in acid solution, red: widely used as a chemical indicator.

litmus

/ ˈlɪtməs /

noun

1. a soluble powder obtained from certain lichens. It turns red under acid conditions and blue under basic conditions and is used as an indicator

litmus

1. A colored powder, obtained from certain lichens, that changes to red in an acid solution and to blue in an alkaline solution. Litmus is a mixture of various closely related heterocyclic organic compounds.

2. ◆ Litmus is typically added to paper to make litmus paper, which can be used to determine whether a solution is basic or acidic by dipping a strip of the paper into the solution and seeing how the paper changes color.

litmus

1. In chemistry, a kind of paper used to tell whether a solution is an acid or a base. Acids turn blue litmus paper red; bases turn red litmus paper blue. Other testing paper or sophisticated instruments can be used to measure the pH of a solution more precisely.

The term litmus is often used to refer to a general and simple test: “Your vote on this issue is a litmus test of your political philosophy.”

Word History and Origins

Origin of litmus¹

1495–1505; earlier lytmos < Old Norse litmosi dye-moss, equivalent to lit- color, dye + mosi moss

Word History and Origins

Origin of litmus¹

C16: perhaps from Scandinavian; compare Old Norse litmosi, from litr dye + mosi moss

Example Sentences

The clearest emerging litmus test is opposition to sending offensive weapons, but other issues could loom large in Democratic primaries, including recognizing a Palestinian state and allowing international investigations of Israeli war crimes.

From Salon

“It’s such an important litmus test for me. People would come over and be like, ‘uhh,’” she said of previous dates.

From Los Angeles Times

On the right, this can take the form of conspiracies or authoritarian nostalgia; on the left, it may manifest as moral purism or ideological litmus tests.

From Salon

The heat is a litmus test of where my mental edges are at — how long I need to return to my body after the week’s stresses.

From Los Angeles Times

The provocative images that Mike White leaves viewers to consider provide a litmus test of our own hidden desires and twisted worldviews.

From Salon