Definify.com
Webster 1913 Edition
Litmus
Lit′mus
,Noun.
[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. ☞ 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.