Synonyms: alibi, self-justification, exculpation, excuse
Definition: a defense of some offensive behavior or some failure to keep a promise etc.
Usage: he kept finding excuses to stay; every day he had a new alibi for not getting a job; his transparent self-justification was unacceptable
Similar words: defence, defense, vindication
Definition: the justification for some act or belief
Usage: he offered a persuasive defense of the theory