alibi

Short definition from Wiktionary

Noun

1. 1
   The plea or mode of defense under which a person on trial for a crime proves or attempts to prove being in another place when the alleged act was committed.
2. 2
   An excuse, especially one used to avoid responsibility or blame.

Verb

1. 1
   To provide an alibi for.
2. 2
   To provide an excuse for.