Litmus

n.

1.

(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. Litmus paper (Chem.) unsized paper saturated with blue or red litmus, - used in testing for acids or alkalies.

Noun

1.

litmus - 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 Synonyms: litmus test

acid-base indicator, litmus paper, litmus test