An Etymological Dictionary of the German Language/schnell
schnell, adj., ‘quick, speedy, hasty,’ from MidHG. snël (ll), adj., ‘quick, nimble, brave,’ OHG. snël (ll); comp. OSax. and AS. snël (ll), ‘fresh, energetic, courageous,’ Scotch snell, ‘bitter’ (comp. E. keen in the same sense, ModHG. kühn), Du. snel, OIc. snjallr, ‘eloquent, capable, brave.’ The earlier meaning (comp. the ModHG.), was much more general, equiv. perhaps to ‘capable’; comp. bald. This common Teut. adj., unknown only to Goth., passed into Rom.; comp. the cognates of Ital. snello, ‘quick, lively.’ The origin of the Teut. adj. is obscure. — Comp. Schnalle. ModHG. schnellen, vb., ‘to jerk, toss,’ from MidHG. snellen (pret. snalte), ‘to send off with a jerk; move on rapidly.’