(ălʹə-bī´) noun. 1. 1. Law. a. A form of defense whereby a defendant attempts to prove that he or she was elsewhere when the crime in question was committed. b. The fact of having been elsewhere when a crime in question was committed. 2. Usage Problem. An explanation offered to avoid blame or justify action; an excuse, alibi: to prove an alibi, membuktikan alibi: 2. (colloquial) excuse, alasan, dalih.