On the contrary, but rather (introducing a word or clause that contrasts with or contradicts the preceding clause or sentence without the not).
However, although, nevertheless (implies that the following clause is contrary to prior belief or contrasts with or contradicts the preceding clause or sentence).
Except that (introducing a subordinate clause which qualifies a negative statement); also, with omission of the subject of the subordinate clause, acting as a negative relative, "except one that", "except such that".
(archaic) Without its also being the case that; unless that (introducing a necessary concomitant).
