litmus

noun

lit·​mus ˈlit-məs 

1

: a coloring matter from lichens that turns red in acid solutions and blue in alkaline solutions and is used as an acid-base indicator

2

: the critical factor in a litmus test

also : litmus test

Examples of litmus in a Sentence

Recent Examples on the Web

Alpert maintains that his litmus for music has remained the same throughout the decades. —Gary Graff, Billboard, 26 Sep. 2024

Looking into next year, Fallout will be an early litmus. —Will Bedingfield, WIRED, 28 Dec. 2023

Rahmani pointed to Smollett’s forfeiture of his $10,000 bond as a litmus not only for punishment but acceptance of the Foxx agreement. —Fox News, 17 Mar. 2022

The 2023 roster will feature two players who could represent litmus tests for how aggressively the Sox will approach such extensions: righthander Brayan Bello and first baseman Triston Casas. —Alex Speier, BostonGlobe.com, 27 Jan. 2023

Word History

Etymology

Middle English litmose, of Scandinavian origin; akin to Old Norse litmosi herbs used in dyeing, from litr color (akin to Old English wlite brightness, appearance) + mosi moss; akin to Old English mōs moss

First Known Use

14th century, in the meaning defined at sense 1

Phrases Containing litmus

• litmus paper
• litmus test

Medical Definition

litmus

noun

lit·​mus ˈlit-məs 

: a coloring matter from lichens that turns red in acid solutions and blue in alkaline solutions and is used as an acid-base indicator