LITMUS

litmus, litmus test

(noun) a coloring material (obtained from lichens) that turns red in acid solutions and blue in alkaline solutions; used as a very rough acid-base indicator

Source: WordNet® 3.1

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Etymology

Noun

litmus (countable and uncountable, plural litmuses)

(uncountable) A dyestuff extracted from certain lichens, that changes color when exposed to pH levels greater than or less than certain critical levels.

A simple test of acidity in a liquid using litmus, usually in the form of litmus paper.

A simple test of any attribute; a litmus test.

Synonyms

• (dyestuff from lichen): lacmus

Anagrams

• multis, slum it, sultim, tilmus

Source: Wiktionary

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Lit"mus, n. Etym: [D. lakmoes; lak lacker + moes a thick preparation of fruit, pap, prob. akin to E. meat: cf. G. lackmus. See Lac a resinous substance.] (Chem.)

Definition: A dyestuff extracted from certain lichens (Roccella tinctoria, Lecanora tartarea, etc.), as a blue amorphous mass which consists of a compound of the alkaline carbonates with certain coloring matters related to orcin and orcein.

Note: Litmus is used as a dye, and being turned red by acids and restored to its blue color by alkalies, is a common indicator or test for acidity and alkalinity. Litmus paper (Chem.), unsized paper saturated with blue or red litmus, -- used in testing for acids or alkalies.

Source: Webster’s Unabridged Dictionary 1913 Edition

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