- a test using litmus, esp. litmus paper, to determine whether a solution is an acid or a base
- any factor regarded as the decisive criterion in assessing the quality or authenticity of someone or something
litmus testlitmus test
- A test for chemical acidity or basicity using litmus paper.
- A test that uses a single indicator to prompt a decision: “The word 'hopefully' has become the litmus test to determine whether one is a language snob or a language slob” ( William Safire )
(plural litmus tests)