The Open Dictionary

litmus

noun

UK/ˈlɪt.məs/
US/ˈlɪt.məs/

Definitions of litmus noun

  1. Uncountable

    A substance, usually in powder form, that changes color to red in acidic conditions and to blue in alkaline conditions.

    • The litmus paper was used to test the acidity of the solution.

    • The chemical experiment used litmus to indicate changes in pH.

    • Litmus is a useful chemical indicator.