"suburb," late 15c., from Middle French faux bourg, said by French authorities to be from Old French forsbourc (12c.) "suburbs, outskirts," literally "that which is outside the town," from fors "outside" (from Latin foris; see foreign) + bourc "town" (a word of Frankish origin cognate with English borough), and altered in Middle French by folk-etymology to faux bourg "false town" (suburbs were seen as inauthentic).