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.
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.
break one's word
Violate or fail to observe a promise or contract one has made. For example, You can trust him implicitly; I've never known him to break his word. [c. a.d. 1000]
keep/break your ˈword
do/fail to do what you have promised: Do you think she’ll break her word and tell everyone?