Litmus Test Has Scientific Origins

It was in the 14th century that scientists discovered that litmus, a mixture of colored organic compounds obtained from lichen, turns red in acid solutions and blue in alkaline solutions and, thus, can be used as an acid-base indicator. Six centuries later, people began using litmus test figuratively. It can now refer to any single factor that establishes the true character of something or causes it to be assigned to one category or another. Often it refers to something (such as an opinion about a political or moral issue) that can be used to make a judgment about whether someone or something is acceptable or not.

Examples of litmus test in a Sentence

The party is using attitudes about gun control as a litmus test for political candidates.

Recent Examples on the Web The strength of Republican candidates’ stances against gender-affirmation therapies became a litmus test for the authenticity of their conservatism in midterm primary races earlier this year. — Michael Murney, Chron, 21 June 2022 But mainly, the purchase of Gray Eagles is a litmus test for just how far the U.S. will go in supporting Ukraine against the Russian invasion. — David Hambling, Forbes, 21 June 2022 Part of the dilemma, according to people familiar with the internal deliberations, is that Mr. Biden’s approach is likely to be seen as a litmus test by many centrist or liberal-leaning voters. — New York Times, 16 June 2022 But the governor also nodded to the way bills targeting transgender youth have become a litmus test for the Republican Party at large. — Washington Post, 23 Mar. 2022 Baltin: Do you guys see this as a little bit of a litmus test for possibly doing something like this going forward? — Steve Baltin, Forbes, 8 June 2022 Jewish students at Tufts and other campuses said that many campus clubs, even those that are not explicitly political, have taken a hard line on Israel, which can create an obstacle — even a litmus test — for some Jewish students’ participation. — Globe Staff, BostonGlobe.com, 14 May 2022 Have the candidates in Ohio been made to submit to a kind of Trump-2020-election-claims litmus test? — The New Yorker, 3 May 2022 Or a litmus test in terms of finding the right fit there? — Matt Wake | Mwake@al.com, al, 3 May 2022 See More

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

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