litmus test

noun

: a test in which a single factor (such as an attitude, event, or fact) is decisive

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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 something 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
Examples are automatically compiled from online sources to show current usage. Read More Opinions expressed in the examples do not represent those of Merriam-Webster or its editors. Send us feedback.
By Jonathan Beeby, managing director, SAP Concur Australia and New Zealand Business travel has become a litmus test for how organisations adapt to modern working norms, evolving employee expectations, and ongoing cost-control pressures. Forbes.com, 2 July 2025 The pledge became a litmus test for fiscally conservative GOP candidates and cemented the party’s anti-tax stance. Drew Kurlowski, The Conversation, 25 June 2025 Before Tuesday night’s game, interim manager Warren Schaeffer agreed that facing quality teams like the defending World Series champion Dodgers was, indeed, a litmus test. Patrick Saunders, Denver Post, 24 June 2025 The transaction is contingent on regulatory approval and could be a litmus test for President Donald Trump’s views on major companies combining. Jordan Valinsky, CNN Money, 16 May 2025 See All Example Sentences for litmus test

Word History

First Known Use

1913, in the meaning defined above

Time Traveler
The first known use of litmus test was in 1913

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Cite this Entry

“Litmus test.” Merriam-Webster.com Dictionary, Merriam-Webster, https://www.merriam-webster.com/dictionary/litmus%20test. Accessed 11 Jul. 2025.

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