'Litmus' definitions:
Definition of 'litmus'
From: WordNet
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 [syn: litmus, litmus test]
Definition of 'Litmus'
From: GCIDE
- Litmus \Lit"mus\, n. [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.) 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. [1913 Webster]
- 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. [1913 Webster]
- Litmus paper (Chem.), unsized paper saturated with blue or red litmus, -- used in testing for acids or alkalies. [1913 Webster]