Mum's the word is an English idiom for keeping silent.
Mum's the Word may also refer to:
Mum's the Word (film), a 1996 Canadian documentary short film Kingsman: Mum's the Word, a 2016 British one-shot comic book in the Kingsman franchise "Mum's the Word" (Bless This House), a 1971 television episode "Mum's the Word" (Miranda), also known as "Holiday", a 2009 television episode
See also "Mom's the Word", a 2014 episode of Family Guy "Mom's the Word!", a 1988 episode of The Raccoons