köken: Unadapted borrowing from English bacon, from Middle English bacon (“meat from the back and sides of a pig”), from Old French bacon, bacun (“ham, strip of lard”), from Frankish *bakkō, from Proto-Germanic *bakō, *baką, *bakaz (“back”), from Proto-Indo-European *bʰeg- (“back, buttocks; to vault, arch”). Attested since 1899.
side, edge; margin, brim etc. · side, a location outside or away from something
köken: From *čet (“edge, border; a location aside/away from sth.; foreign”). Cognate with Kazakh шет (şet, “edge”), Kyrgyz чет (cet, “edge”), Southern Altai чет (čet, “corner, edge”), Uzbek chet (“edge”), Uyghur چەت (chet, “edge”), Shor чет (“border”), etc.
köken: It is attested as Bordas (personal name, 1355), bõda (“loom comb”) (1405). The meaning "rib" is attested since 1578. Ultimately from a Slavic language; compare Proto-Slavic *bьrdo.
From Proto-Finnic *külki (compare Estonian külg, Veps külʹg). Initially likely an anatomical term, although it has also developed the more abstract meaning “side” in most other Finnic languages as well.