early 14c., las "a blow, a stroke," later "flexible part of a whip" (late 14c.), possibly imitative. The verb "to strike out" is first attested early 14c. and may be the source of the noun. Lash out "to strike out violently" is from 1560s. Related: Lashed; lashes; lashing.
"bind," 1620s, originally nautical, from M.Fr. lachier, from O.Fr. lacier "to lace" (see lace).