1. Excuse, forgive, pardon imply being lenient or giving up the wish to punish. Excuse means to overlook some (usually) slight offense: to excuse bad manners. Forgive is applied to excusing more serious offenses: to forgive and forget. Pardon usually applies to a specific act of lenience or mercy by an official or superior: The governor was asked to pardon the condemned criminal. 8. Excuse, apology both imply an explanation of some failure or failing. Excuse implies a desire to avoid punishment or rebuke. Apology usually implies acknowledgment that one has been in the wrong.

Did you mean inexcusable?