but

But is normally categorised as a conjunction, but it behaves quite differently from and and or.

But is highly constrained in the kinds of structures it can coordinate. It does not conjoin nouns or noun phrases, one of the most common functions of the other two conjunctions; it occasionally conjoins modal auxiliaries---she can but won't help me; it sometimes conjoins adjectives---They are poor but happy. Most often but conjoins predicates and independent clauses.


I like Meg but I can't stand her brother.