renege

/rɪˈnɪɡ/

Other forms: reneged; reneging; reneges

To renege is to go back on your word or fail to keep a promise.

Not quite lying, reneging is more a sin of omission — failing to do what you said you would. The Latin negāre means "to deny," so by reneging on your word, you are denying someone whatever you promised them. In card games, you are said to renege if you play against the rules. To renege may be wrong, but it's not necessarily a punishable offense (unless you put that promise legally binding in writing). Still, it certainly doesn't make you look good!

Definitions of renege

1. verb

   fail to fulfill a promise or obligation
   synonyms: go back on, renege on, renegue on

   type of:

   annul, countermand, lift, overturn, repeal, rescind, reverse, revoke, vacate

   cancel officially
2. noun

   the mistake of not following suit when able to do so
   synonyms: revoke

   type of:

   error, fault, mistake

   a wrong action attributable to bad judgment or ignorance or inattention