|1.||mums the word|
to keep quiet about something
I heard Elaine's parents are out of town tonight and she's lonely! I'm gonna go over. Mums the word!
|2.||mums the word|
to keep quiet about something; my lips are sealed.
mum means mmmmmm (the sound made when putting your lips together)
came from Shakespeare quote:
"Seal up your lips and give no words but mum."
person 1: "Please don't tell anyone about my affair."
person 2: "Don't worry i won't. Mums the word."