"but" is a conjuction, signifying an alterate aspect in a sentence. It
can also mean in exception.
From M-W.com,
"
Etymology: Middle English, from Old English butan, preposition &
conj., outside, without, except, except that; akin to Old High German
buzan without, except; akin to Old English be by, ut out -- more at
BY, OUT
1 a : except for the fact <would have protested but that he was
afraid> b : THAT -- used after a negative <there is no doubt but he
won> c : without the concomitant that <it never rains but it pours> d
: if not : UNLESS e : THAN <no sooner started but it stopped> -- not
often in formal use
2 a : on the contrary : on the other hand : NOTWITHSTANDING -- used to
connect coordinate elements <he was called but he did not answer> <not
peace but a sword> b : YET <poor but proud> c : with the exception of
-- used before a word often taken to be the subject of a clause <none
but the brave deserves the fair -- John Dryden>
- but what : that... not -- used to indicate possibility or
uncertainty <I don't know but what I will go>
" |
