What is the X in X-mas?
early 13c., from Old French rute "road, way, path" (12c.), from Latin rupta (via) "(a road) opened by force," from rupta, fem. past participle of rumpere "to break" (see rupture (n.)). Sense of "fixed or regular course for carrying things" (cf. mail route) is 1792, an extension of the meaning "customary path of animals" (early 15c.).
1890, from route (n.). Related: Routed; routing.