well-nigh vs almost

well-nigh and almost both are adverbs.

Word	Noun	Adjective	Verb	Adverb
well-nigh	No	No	No	Yes
almost	No	No	No	Yes

As adverbs, well-nigh and almost are synonyms defined as:

well-nigh and almost: (of actions or states) slightly short of or not quite accomplished; all but

Other synonyms of well-nigh include about, most, near, nearly, nigh, virtually.

well-nigh (adverb)	almost (adverb)
(of actions or states) slightly short of or not quite accomplished; all but	(of actions or states) slightly short of or not quite accomplished; all but