Etymology: < Old Northern French walop (found in 13th cent. in plural walos ) = French galop , related to galoper to gallop: see wallop v. There is nothing to show whether the verb or the noun is the earlier formation in Old French Both were introduced together into Middle English in sense 1, appearing first in the 14th cent.; but in later use in all senses the noun is more often to be regarded as newly formed from the verb in its later applications, and with its onomatopoeic and humorous connotation. The form gallop n. appears first in the 16th cent. and replaces wallop , noun, in the original and more elevated sense, in which, however, wallop v. continues to be evidenced.

Etymology: < Old Northern French *waloper = French galoper (see gallop v.¹). The existence of this form is evidenced in addition to the English forms by Old French walos noun plural and the adopted form Flemish walop(pe, Middle High German walop, walap noun, Middle High German walopiren, verb, and probably by modern Walloon (Sigart) waloper to rinse linen in water. Compare Norwegian (Aasen) val(l)hoppa vb., apparently an etymologizing alteration, after Norwegian hoppa to leap, dance.A satisfactory origin for this word in French has not been suggested. It is probably purely echoic, or an echoic alteration of some Germanic element or elements. The Provençal form galaupar has suggested Germanic *ga-hlaupan (Old English gehléapan , < ge- y- prefix + hléapan to leap v.), but the evidence for original w- precludes the comparison of the initial element. In English the onomatopoeic suggestion of the word has lent itself to varied extension of meanings and to a vague (usually colloquial and humorous) application to violent noisy movements, more especially since the form gallop v.¹ ousted it from the more elevated uses (in the course of the 16th cent.). The sense ‘to boil rapidly’ is probably derived directly by transference from sense 1 (compare gallop v.² to boil) in spite of the close resemblance of the word to wall v.¹ + up adv.¹ (compare well up , and Dutch opwallen ). The relation of potwalloper n. to potwaller n. indicates that some such association was active. The sense ‘to beat’ may be ultimately due to the causative use (sense 2, and compare French galoper transitive), or may be entirely due to onomatopoeic extension.