c.1300, "to rush, plunge, leap, start forth; to be set into sudden motion," from Old North French lancher (Old French lancier) "to fling, hurl, throw, cast," from Late Latin lanceare "wield a lance," from Latin lancea "light spear" (see lance). Sense of "set (a boat) afloat" first recorded c.1400, from notion of throwing it out on the water; generalized by 1600 to any sort of beginning. The noun meaning "a leap or a bound" is from mid-15c., from the verb. Meaning "the liftoff of a missile, spacecraft, etc." is from 1935. Launch pad attested from 1960.