Definition of alibi:
(n) :
the plea or mode of defense under which a person on trial for a crime proves or attempts to prove that he was in another place when the alleged act was committed; as, to set up an alibi; to prove an alibi. The Criminal Law Deskbook (1988; ISBN 0820512176) states: "Alibi is different from all of the other defenses...it is based upon the premise that the defendant is truly innocent."
(v) :
to provide an
alibi for; to provide an
excuse for