An Etymological Dictionary of the German Language/Annotated/Galopp
Galopp, masculine, ‘gallop,’ borrowed from French galop, even in the Middle High German period, as is proved by Middle High German galopieren, of which the variant walopieren occurs (compare Middle High German walap, ‘galop,’ English wallop). The Romance words on which they are based are derived by some etymologists from a Teutonic source, though it cannot be assigned to any satisfactory root; some assume a Goth-Teutonic *walh-hlaup, which is supposed to denote a Keltic method of trotting.