Real Dictionary

alibi
countable noun: If you have an alibi, you can prove that you were somewhere else when a crime was committed.
countable noun: You can say that someone has an alibi when they can prove that something was not their fault.

alibi in American English
the defensive plea or fact that an accused person was elsewhere than at the scene of the crime with which the person is charged
to offer an excuse (for)
intransitive verb: to give an excuse; offer a defense
noun: the defense by an accused person of having been elsewhere at the time an alleged offense was committed
transitive verb: to provide an alibi for (someone)

alibi in British English
noun: a defence by an accused person that he or she was elsewhere at the time the crime in question was committed
verb: to provide with an alibi