litmus test
noun
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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 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
Dr. Jonathan Reichental, Forbes.com, 8 June 2025
Biden's cognitive decline has become the defining litmus test for Democrats now jockeying to inherit a party still reeling from Trump's return to the White House.
—Carlo Versano, MSNBC Newsweek, 20 May 2025
United march through threadbare City to Wembley Sunday represented the first of six season-defining litmus tests for United in the newest edition of the Skinner era and United can now emphatically check one off that list.
—Megan Feringa, New York Times, 13 Apr. 2025
For Trump, trade is not merely an economic issue, but a litmus test of whether America is winning or losing on the world stage.
—Ryan Hass, Time, 30 May 2025
See All Example Sentences for litmus test
Cite this Entry
“Litmus test.” Merriam-Webster.com Dictionary, Merriam-Webster, https://www.merriam-webster.com/dictionary/litmus%20test. Accessed 16 Jun. 2025.
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