litmus test

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

лакмусовая бумажка

Did you know?
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. Opinions expressed in the examples do not represent those of Merriam-Webster or its editors. Send us feedback.
Toronto’s proposed urban project, Sidewalk, haunts both the city and the developers, and is a litmus test for cognitive technology use, as issues surrounding privacy and data contributed greatly to its abandonment.
—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

Word History
First Known Use
1913, in the meaning defined above

Time Traveler
The first known use of litmus test was in 1913
See more words from the same year