1. If it were not for the fact that; only. Often used with that: I would buy the suit, except that it costs too much.
2. Otherwise than: They didn't open their mouths except to complain.
3. Unless: "And ne'er throughout the year to church thou go'st/Except it be to pray against thy foes" (Shakespeare).

Usage Note: Except in the sense of "with the exclusion of" or "other than" is generally viewed as a preposition, not a conjunction. Therefore, a personal pronoun that follows except should be in the objective case: No one except me knew it. Everyone had a ticket except her.