noun

1. An operation that reverses a previous action.

   “How many undos does this program support?”

verb

1. To reverse the effects of an action.

   “Fortunately, we can undo most of the damage to the system by the war.”

2. To unfasten.

   “Could you undo my buckle for me?”

3. To impoverish or ruin, as in reputation; to cause the downfall of.

Synonyms: cancel, reverse, unbuckle, unbutton, untie, unzip