Definition of litmus in English:


Syllabification: lit·mus
Pronunciation: /ˈlitməs


  • A dye obtained from certain lichens that is red under acid conditions and blue under alkaline conditions.
    More example sentences
    • In the presence of a basic solution, litmus will lose hydronium ions and turn blue.
    • During the 1660s, Robert Boyle discovered that certain plant extracts, such as litmus, can be used to distinguish acids from bases.


Middle English: from Old Norse lit-mosi, from litr 'dye' + mosi 'moss'.

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Pronunciation: məˈlôrd
used to address an English nobleman