From Longman Dictionary of Contemporary Englishlitmuslit‧mus /ˈlɪtməs/ noun [uncountable] HCa chemical that turns red when it touches acid, and blue when it touches an alkali
Examples from the Corpus
litmus• The case of travellers is something of a litmus test.• Forbes, meanwhile, has made winning Arizona his litmus test for capturing the nomination.• The use of litmus paper furnishes another example of such a transformation.• What clearer laboratory or litmus test could there be to show that our methods are genuinely additional?• He instituted a stringent litmus test on doctrinal matters.• In a drawer the litmus paper mused upon which way to turn.• Comparison is the only true litmus test of objectivity.Origin litmus (1300-1400) Old Norse litmosi, from litr “coloring substance” + mosi “moss” 