Cambridge Dictionaries online Cambridge Dictionaries online

The most popular online dictionary and thesaurus for learners of English


English definition of “mum”


adjective [not gradable] (SILENT)   /mʌm/
silent in order not to tell anyone what you know : The governor is keeping mum about his plans .
(Definition of mum adjective (SILENT) from the Cambridge Academic Content Dictionary © Cambridge University Press)
Focus on the pronunciation of mum

Definitions of “mum” in other dictionaries

Word of the Day


relating to behaviour between people that is pleasant and friendly, often despite a difficult situation

Word of the Day


Read our blog about how the English language behaves.

Learn More

New Words

Find words and meanings that have just started to be used in English, and let us know what you think of them.

Learn More