An Etymological Dictionary of the German Language/Annotated/schnell
schnell, adjective, ‘quick, speedy, hasty,’ from Middle High German snël (ll), adjective, ‘quick, nimble, brave,’ Old High German snël (ll); compare Old Saxon and Anglo-Saxon snël (ll), ‘fresh, energetic, courageous,’ Scotch snell, ‘bitter’ (compare English keen in the same sense, Modern High German kühn), Dutch snel, Old Icelandic snjallr, ‘eloquent, capable, brave.’ The earlier meaning (compare the Modern High German), was much more general, equivalent perhaps to ‘capable’; compare bald. This common Teutonic adjective, unknown only to Gothic, passed into Romance; compare the cognates of Italian snello, ‘quick, lively.’ The origin of the Teutonic adjective is obscure. — Compare Schnalle. Modern High German schnellen, verb, ‘to jerk, toss,’ from Middle High German snellen (preterite snalte), ‘to send off with a jerk; move on rapidly.’