Wiktionary
vb. 1 (context transitive English) To be treacherous or faithless to; betray. 2 (context transitive English) To fail to keep; to renege on.
WordNet
v. fail to fulfill a promise or obligation; "She backed out of her promise" [syn: renege, renege on, renegue on]
Usage examples of "go back on".
I didn't want to increase his aggravation for fear he would go back on his promise to hire additional staff and give the children more freedom to get on with their own work.
He had careened the vessel, cleaned her up and rerigged her, and it was obvious that he intended to violate his pardon and go back on the account.
But I just need to know, so I can get myself together and go back on the street, and get a job to support your golfing.
It was impossible to go back on one's word without admitting to it.
Varian gestured for him to go back on the tape until she had the frame of the creature, suspended in its flight, its crested head slightly turned toward the camera so that both golden-colored eyes were visible.