a claim or piece of evidence that one was elsewhere when an act, typically a criminal one, is alleged to have taken place.
"she has an alibi for the whole of yesterday evening"
offer an excuse or defense for (someone), especially by providing an account of their whereabouts at the time of an alleged act.
"her friend agreed to alibi her"
synonyms: cover for, give an alibi to, provide with an alibi, shield, protect
"her brother had reluctantly agreed to alibi her"