quite: [14] Quite is essentially the same word as the adjective quit ‘free, absolved, discharged, cleared’ (which in Middle English commonly took the alternative form quite). It came to be used as an adverb meaning ‘thoroughly, clearly’. The weaker modern sense ‘fairly’ did not develop until as recently as the mid-19th century. => quit[quite etymology, quite origin, 英语词源]
early 14c., adverbial form of Middle English quit, quite (adj.) "free, clear" (see quit (adj.)). Originally "thoroughly;" the weaker sense of "fairly" is attested from mid-19c.