excuse vs alibi

excuse and alibi both are nouns.

Word	Noun	Adjective	Verb	Adverb
excuse	Yes	No	Yes	No
alibi	Yes	No	Yes	No

As nouns, excuse and alibi are synonyms defined as:

excuse and alibi: a defense of some offensive behavior or some failure to keep a promise etc.

Other synonyms of excuse include exculpation, self-justification.

As verbs, alibi is a hyponym of excuse; that is, alibi is a word with a more specific, narrower meaning than excuse:

excuse (noun)	alibi (noun)
a poor example	(law) a defense by an accused person purporting to show that he or she could not have committed the crime in question
a defense of some offensive behavior or some failure to keep a promise etc.	a defense of some offensive behavior or some failure to keep a promise etc.
a note explaining an absence

excuse (verb)	alibi (verb)
accept an excuse for	exonerate by means of an alibi
defend, explain, clear away, or make excuses for by reasoning
excuse, overlook, or make allowances for; be lenient with
serve as a reason or cause or justification of
grant exemption or release to
ask for permission to be released from an engagement