| 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. ] (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 ] ☞ 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 ]
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| litmus test | 1. (Chem.) A test to determine acidity or alkalinity, using litmus as an inddicator. [ PJC ] 2. Hence: (Fig.) A test for a single factor, which has only two outcomes, positive or negative; specifically: (Politics) the question of whether a candidate for office is for or against a particular position on an issue; -- used, e.g. by voters concerned predominantly with a single issue, to decide whether to vote for or against a candidate; as, many voters take a candidate's position on abortion as their litmus test. [ PJC ] |
