Merriam-Webster's Collegiate® Dictionary, 11th Edition
WALLOP
I. verb
Etymology: Middle English walopen to gallop, from Old French (Picard dialect) waloper
Date: 1579
intransitive verb to boil noisily,
2. to move with reckless or disorganized haste ; advance in a headlong rush, wallow , flounder , transitive verb
1. to thrash soundly ; lambaste , to beat by a wide margin ; trounce , to hit with force ; sock , walloper noun
II. noun
Date: circa 1823
1. a powerful blow ; punch , something resembling a wallop especially in suddenness of force, the ability (as of a boxer) to hit hard,
2. emotional, sensory, or psychological force or influence ; impact , an exciting emotional response ; thrill , beer