litmus

• POS: Noun
• HYPHEN: lit=mus

CIDE DICTIONARY

litmus, 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.].

 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]
" 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.

OXFORD DICTIONARY

litmus, n. a dye obtained from lichens that is red under acid conditions and blue under alkaline conditions.

Idiom

litmus paper a paper stained with litmus to be used as a test for acids or alkalis.

Etymology

ME f. ONorw. litmosi f. ON litr dye + mosi moss