History and Etymology
Conjunction, Preposition, Adverb, and Pronoun
Middle English, from Old English
būtan, preposition & conjunction, outside, without, except, except that; akin to Old High German
būzan without, except; akin to Old English
be by,
ūt out — more at
by entry 1,
out entry 1Noun
Scots
but, adjective (outer)