verb
(transitive) To exclude; to specify as being an exception.
(intransitive) To take exception, to object (to or against).
preposition
Used to introduce an exception or qualification to something previously stated.
conjunction
Used to introduce a clause, phrase, verb infinitive, adverb or other non-noun complement forming an exception or qualification to something previously stated.
(informal) Loosely, used to introduce a contrastive statement explaining why something wasn't successful, didn't happen, etc.
(archaic) Unless; used to introduce a hypothetical case in which an exception may exist.