Farewell

google

ref

late Middle English: from the imperative of fare + the adverb well1.

wiktionary

ref

From Middle English farewel, from fare wel!, an imperative expression, possibly further derived from Old English* far wel!, equivalent to fare(“to fare, travel, journey”) +‎ well. Compare Scots farewele, fairweill(“farewell”), Saterland Frisian Foarwäil(“farewell”), West Frisian farwol(“farewell”), East Frisian forwal [1], Dutch vaarwel(“farewell (sadly)”), Danish farvel(“farewell”), Norwegian farvel(“farewell”), Swedish farväl(“farewell”), Faroese farvæl(“goodbye”), Icelandic far vel(“farewell”). The extensive list of cognates suggests a postulated ultimate Proto-Germanic phrase of origin, possibly something akin to *far wela.

etymonline

ref

farewell (interj.)

expression at parting, late 14c., from Middle English faren wel, verbal phrase attested by c. 1200 (see fare (v.) + well (adv.)); usually said to the departing person, who replied with good-bye. As a noun, "a good-bye, a leave-taking," by early 15c. Expression to a fare-thee-well "to the last degree" is by 1884, American English.