From PIE *welh₁- (to wish, to choose) — 'well' originally meant 'as wished,' kin to 'will' and 'wealth.'
In a good or satisfactory manner; thoroughly; to a considerable degree. Also a noun meaning a shaft for water and an interjection used to introduce remarks.
From Old English 'wel' (well, abundantly, satisfactorily), from Proto-Germanic *welō (well, abundantly), from PIE *welh₁- (to wish, to will, to choose). The adverb is intimately related to 'will' and 'wealth' — all from the same root expressing desire and choice. Something done 'well' was originally something done 'as one would wish