litmus

American

[lit-muhs] / ˈlɪt məs /

noun

a blue coloring matter obtained from certain lichens, especially Roccella tinctoria. In alkaline solution litmus turns blue, in acid solution, red: widely used as a chemical indicator.

litmus British

/ ˈlɪtməs /

noun

a soluble powder obtained from certain lichens. It turns red under acid conditions and blue under basic conditions and is used as an indicator

"Collins English Dictionary — Complete & Unabridged" 2012 Digital Edition © William Collins Sons & Co. Ltd. 1979, 1986 © HarperCollins Publishers 1998, 2000, 2003, 2005, 2006, 2007, 2009, 2012

litmus Scientific

/ lĭt′məs /

A colored powder, obtained from certain lichens, that changes to red in an acid solution and to blue in an alkaline solution. Litmus is a mixture of various closely related heterocyclic organic compounds.
◆ Litmus is typically added to paper to make litmus paper, which can be used to determine whether a solution is basic or acidic by dipping a strip of the paper into the solution and seeing how the paper changes color.

litmus Cultural

In chemistry, a kind of paper used to tell whether a solution is an acid or a base. Acids turn blue litmus paper red; bases turn red litmus paper blue. Other testing paper or sophisticated instruments can be used to measure the pH of a solution more precisely.

Discover More

The term litmus is often used to refer to a general and simple test: “Your vote on this issue is a litmus test of your political philosophy.”

Etymology

Origin of litmus

1495–1505; earlier lytmos < Old Norse litmosi dye-moss, equivalent to lit- color, dye + mosi moss

Example Sentences

Examples are provided to illustrate real-world usage of words in context. Any opinions expressed do not reflect the views of Dictionary.com.

Next week brings one of the markets most crucial litmus tests of the artificial-intelligence trade, when chip maker Nvidia reports earnings on Wednesday.

From The Wall Street Journal

“We are removing litmus tests, not adding them.”

From The Wall Street Journal

Olympic qualification doesn’t involve a political litmus test—only citizenship, sportsmanship and skill.

From The Wall Street Journal

Still, many wondered if the Lakers’ litmus test would come from facing the defending champion Oklahoma City Thunder on Monday night.

From Los Angeles Times

The outcome of the first case will serve as a litmus test of jury reaction to evidence presented by the plaintiffs about whether the companies should be held liable.

From The Wall Street Journal

Definitions and idiom definitions from Dictionary.com Unabridged, based on the Random House Unabridged Dictionary, © Random House, Inc. 2023