An Etymological Dictionary of the German Language/Galopp
Galopp, m., ‘gallop,’ borrowed from Fr. galop, even in the MidHG. period, as is proved by MidHG. galopieren, of which the variant walopieren occurs (comp. MidHG. walap, ‘galop,’ E. wallop). The Rom. words on which they are based are derived by some etymologists from a Teut. source, though it cannot be assigned to any satisfactory root; some assume a Goth-Teut. *walh-hlaup, which is supposed to denote a Kelt. method of trotting.