[noun] [U] - a powder which is turned red by acidThe litmus paper will turn red in an acid and blue in an alkali.You can discover the acidity of the solution with a litmus test.A litmus test is someone's decision or opinion about something which suggests what they think about a wider range of related things.The President's policy on abortion is regarded as a litmus test of his views on women's rights.
LITMUS
Meaning of LITMUS in English
Cambridge English vocab. Кембриджский английский словарь. 2012