Wallop
Middle English (as a noun denoting a horse's gallop): from Old Northern French walop (noun), waloper (verb), perhaps from a Germanic phrase meaning ‘run well’, from the bases of well1 and leap. Compare with gallop. From ‘gallop’ the senses ‘bubbling noise of a boiling liquid’ and then ‘sound of a clumsy movement’ arose, leading to the current senses.
wiktionary
From Middle English wallopen(“gallop”), from Anglo-Norman[Term?], from Old Northern French walop(“gallop”, noun) and waloper(“to gallop”, verb) (compare Old French galoper, whence modern French galoper), from Frankish *wala hlaupan(“to run well”) from *wala(“well”) + *hlaupan(“to run”), from Proto-Germanic *hlaupaną(“to run, leap, spring”), from Proto-Indo-European *klaub-(“to spring, stumble”). Possibly also derived from a deverbal of Frankish *walhlaup(“battle run”) from *wal(“battlefield”) from Proto-Germanic[Term?](“dead, victim, slain”) from Proto-Indo-European *wel-(“death in battle, killed in battle”) + *hlaup(“course, track”) from *hlaupan(“to run”). Compare the doublet gallop.
Clipping of write to all operators.
etymonline
wallop (v.)
late 14c., "to gallop," possibly from Old North French *waloper (13c., Old French galoper), from Frankish compound *walalaupan "to run well" (compare Old High German wela "well," see well (adv.); and Old Low Franconian loupon "to run, leap," from Proto-Germanic *hlaupan; see leap (v.)). The meaning "to thrash" (1820) and the noun meaning "heavy blow" (1823) may be separate developments, of imitative origin. Related: Walloped; walloping.
