Synonyms for All but:

adv

almost (adverb)
well-nigh.

adv.

almost (adverb)
most, just about, virtually, nigh, well-nigh, about.
just about (adverb)
nearly, just about.
most (adverb)
almost.
nearly (adverb)
nearly.
round (adverb)
near.

n.

all but (noun)
well-nigh, just about, nearly, almost, virtually, near, nigh, about, most.

Other synonyms:

Other relevant words:
most.