Synonyms for But:

adv

•however (adverb)
although, still, moreover, yet, however, though, furthermore, nevertheless, Albeit.
•merely (adverb)
simply, just.

adv.

•all (adverb)
merely, just, simply, only.
•however (adverb)
although, still, moreover, yet, however, though, furthermore, nevertheless, Albeit.

conj.

•however (conjunction)
still.

n.

Excepting, beyond, with the exception of, Excluding, exclusive of something, otherwise than. aside from, Without. purely. include. •but (noun)
merely, just, simply, only.

prep.

•indicating an exception (preposition)
aside from, Without.
•indicating contrast (preposition)
however, although, still, nevertheless, though, yet.

Other synonyms:

Excepting. beyond. •Other relevant words:
only, purely, beyond, aside from, include, simply, just, merely, Excepting, Excluding, Without.

Usage examples for but

1. But I do not know you. – Historical Romances: Under the Red Robe, Count Hannibal, A Gentleman of France by Stanley J. Weyman

2. But you don't mean it, do you? – The White Peacock by D. H. (David Herbert) Lawrence

3. But the Delhi Vase! – Sweethearts at Home by S. R. Crockett