1.PrepositionExcept, except for; save for; not counting; were it not for; had it not been for.
"I’d’ve attended but for the fact that the train was late."
2.Prepositiondespite; in spite of
3.AdjectivePertaining to a test of causation whereby an agent or action is considered to have caused an event (and therefore to be responsible and/or liable for said event) if, had said agent or action not existed, the event would not have taken place.