Lash
Middle English (in the sense ‘make a sudden movement’): probably imitative.
wiktionary
From Middle English lashe, lasshe, lasche(“a stroke; the flexible end of a whip”), from Proto-Germanic *laskô(“flap of fabric, strap”).Cognate with Dutch lasch, las(“a piece; seal; joint; notch; seam”), German Low German Laske, Lask(“a flap; dag; strap”), German Lasche(“a flap; joint; strap; tongue; scarf”), Swedish lask(“scarf”), Icelandic laski(“the bottom part of a glove”).
From Middle French lachier, from Old French lacier(“to lace”)
From Old French lasche (French lâche).
etymonline
lash (n.)
c. 1300, las "a blow, a stroke," later "flexible part of a whip" (late 14c.), possibly imitative; compare lash (v.1), which might be the immediate source of this. Century Dictionary says Irish lasg "a lash, whip, whipping" is of English origin. The lash "punishment by flogging" is from 1690s.
lash (v.1)
c. 1300, "to deal a blow;" later "to strike with a whip, beat with a lash" (late 14c.), possibly imitative. To lash out "to strike out violently" (originally of horses) is from 1560s and preserves the older sense. Related: Lashed; lashing.
lash (v.2)
"to tie or bind," as with rope or cord, 1620s, originally nautical, from French lachier, from Old French lacier "to lace on, fasten with laces; entrap, ensnare" (see lace (v.)). Related: Lashed; lashing.
