- go back on one's word
- go back on one's word & go back on one's promise & go back on one's pledgeto break a promise that one has made. •
I hate to go back on my word, but I won't pay you $100 after all.
•Going back on your promise makes you a liar.
* * *{v. phr.} To renege; break a promise. * /Patrick went back on his word when he refused to marry Karen in spite of his earlier promise./
Dictionary of American idioms. 2013.