lit·​mus | \ ˈlit-məs How to pronounce litmus (audio) \

Definition of litmus

1 : a coloring matter from lichens that turns red in acid solutions and blue in alkaline solutions and is used as an acid-base indicator
2 : the critical factor in a litmus test also : litmus test

Examples of litmus in a Sentence

Recent Examples on the Web

Newsom is running to the left of the popular Brown, who is nearly 30 years older, on Democratic litmus-test issues such as single-payer health care for state residents. Scott Wilson, Washington Post, "Think California politics is on the far-left fringe? Just wait for the next elections.," 3 Feb. 2018 The Arizona senator supported Gang of Eight–style immigration reform, when immigration restriction is becoming a litmus-test issue in the party. Rich Lowry, National Review, "Trump Is the GOP Mainstream," 27 Oct. 2017 Let’s use the following multiple-choice criteria as a good litmus. Jeff Sentell, ajc, "What really matters for the nation’s No. 2 OG Trey Hill about choosing a school," 11 Oct. 2017 Cincinnati is more of a litmus for NFL attendance than most places. Paul Daugherty,, "Doc: Are Bengals the canary in NFL coal mine?," 3 Oct. 2017 An early litmus test for UO's potential, and whether that confidence will be realized, will be its Sept. 9 matchup against Nebraska at home. Andrew Greif,, "Oregon Ducks enter Willie Taggart's first season with fresh confidence," 26 Aug. 2017 Navigation functions were simple and quick, a kind of litmus test for the entire infotainment system. Emma Jayne Williams, star-telegram, "New GMC Acadia Denali version gives this SUV the royal treatment," 25 Aug. 2017 This week’s solar eclipse in the U.S. was a litmus test for grid operators. Tim Loh,, "Trump's Coal Push May Be the Disaster Insurance the Grid Doesn’t Need," 24 Aug. 2017 As Politico reports: Taxes, spending and even health care have taken a back seat to the most potent new litmus test in Republican primaries: allegiance to President Donald Trump. Eric Levitz, Daily Intelligencer, "Trump Has Converted the GOP Base to His Ideology: Trump First," 22 Aug. 2017

These example sentences are selected automatically from various online news sources to reflect current usage of the word 'litmus.' Views expressed in the examples do not represent the opinion of Merriam-Webster or its editors. Send us feedback.

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First Known Use of litmus

14th century, in the meaning defined at sense 1

History and Etymology for litmus

Middle English litmose, of Scandinavian origin; akin to Old Norse litmosi herbs used in dyeing, from litr color (akin to Old English wlite brightness, appearance) + mosi moss; akin to Old English mōs moss

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Time Traveler for litmus

The first known use of litmus was in the 14th century

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More Definitions for litmus


lit·​mus | \ ˈlit-məs How to pronounce litmus (audio) \

Medical Definition of litmus

: a coloring matter from lichens that turns red in acid solutions and blue in alkaline solutions and is used as an acid-base indicator

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More from Merriam-Webster on litmus

Spanish Central: Translation of litmus

Nglish: Translation of litmus for Spanish Speakers Encyclopedia article about litmus

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a period when something is suspended

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