keep/break your word

break (one's) word

To fail to act as one has promised. Tom said he'd help us move, but he broke his word and failed to show. If you keep flaking out, you're going to become known as someone who breaks their word.
See also: break, word

keep (one's) word

To do as one has promised. Tom always keeps his word, so if he promised to help you move, then he'll be here.
See also: keep, word
Farlex Dictionary of Idioms.

break one's word

not to do what one said one would do; not to keep one's promise. (Compare this with keep one's word.) Don't say you'll visit your grandmother if you can't go. She hates people to break their word. If you break your word, she won't trust you again.
See also: break, word

keep one's word

to uphold one's promise; to do as one says. (The opposite of break one's word.) I told her I'd be there to pick her up, and I intend to keep my word. Keeping one's word is necessary in the legal profession.
See also: keep, word
McGraw-Hill Dictionary of American Idioms and Phrasal Verbs.

keep/break your ˈword

do/fail to do what you have promised: Do you think she’ll break her word and tell everyone?
See also: break, keep, word
Farlex Partner Idioms Dictionary
See also:
  • break (one's) word
  • break one's word
  • break word
  • be on a hiding to nothing
  • break faith with (someone or something)
  • break/keep faith with somebody
  • fall flat
  • become unglued
  • stop at
  • stop at (something)