IdiomDaily LifeEnglish

mum's the word

Meaning: Keep this secret; say nothing.

Example: “We're planning a surprise party, so mum's the word.”

Origin: "Mum" imitates the sound made with closed lips. It is found in Shakespeare's Henry VI, Part 2 (around 1591): "Seal up your lips and give no words but mum."

Equivalents in other languages

See all 5 languages side by side →

More English idioms

Explore another collection: Untranslatable Words

Words that capture a feeling or idea English needs a whole sentence for.

  • Hiraeth A homesickness for a home you can't return to, or perhaps never had — a grief for lost pl…
  • Madrugada The liminal hours between midnight and sunrise — that strange, quiet time when the night…
  • Duende A mysterious quality in art or performance that moves you to your core — a dark, soulful,…

Browse all untranslatable words →

Keep exploring

Explore all idioms →