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

/ lĭt′məs /

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.

Notes

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

Aaronson figured it would be much easier to solve the system minus one of the 11 rules—leaving a “Collatz-like” system, a litmus test for the larger goal.

From MIT Technology Review

Such litmus tests have not applied in Democratic races this year.

From Washington Post

Cohorts identify these user traits without compromising the user’s privacy, passing a critical litmus test for any viable targeting or measurement solution as programmatic marketing moves toward the post-cookie era.

From Digiday

The problem with this particular litmus test is, it’s not about policy and it’s anti-democratic.

From FiveThirtyEight

Political parties have had plenty of litmus tests over the decades — positions you almost have to have to be a member in good standing.

From FiveThirtyEight

Again, that pre-communion questionnaire sin litmus test might prove handy.

From The Daily Beast

Applying an ideological litmus test for commencement speakers is not a good idea.

From The Daily Beast

But when did they become the litmus test of competence in office?

From The Daily Beast

So they are a litmus paper for wider fertility—not a significant driver of Israeli birthrates.

From The Daily Beast

Opposition to the Affordable Care Act in toto might linger as a litmus test for conservatives.

From The Daily Beast

The solution of lead must contain acid; and if by keeping it does not change litmus-paper, acid must be added till it does.

From Project Gutenberg

The blue litmus paper became red showing the presence of an acid.

From Project Gutenberg

When the small residue was completely dry, it was a yellow solid soluble in dilute alcohol and acid to litmus.

From Project Gutenberg

Vapors and liquid were given off, both of which turned red litmus blue and had a strong odor like tobacco smoke.

From Project Gutenberg

This is an indicator for bases and acids, like litmus, but it is less sensitive to hydroxide-ion than is litmus.

From Project Gutenberg