litmus test

noun

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

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 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

What should be, in theory, an enticing battle for the title of best red-ball country has failed the litmus test in structure and appeal. —Tim Ellis, Forbes.com, 24 Apr. 2025

Father of the last living American hostage in Gaza hopes Trump can bring his son home Walters: UC abandons diversity litmus test for faculty. —Joe Mathews, The Mercury News, 21 Mar. 2025

The April 1 election will be a litmus test early in Trump’s term in a key presidential swing state. —Scott Bauer, Chicago Tribune, 8 Mar. 2025

In his postgame news conference, Lloyd called Houston a great litmus test. —Doug Haller, The Athletic, 16 Feb. 2025

Word History

First Known Use

1913, in the meaning defined above

Rhymes for litmus test

• acquiesced
• coalesced
• dispossessed
• manifest
• overdressed
• overstressed
• prepossessed
• reassessed
• reinvest
• repossessed
• unaddressed
• uncompressed