To hit someone or something hard — one heavy blow, with the sound of it. 'He whopped the ball right over the fence.' It can also mean to beat someone badly in a game or a fight: 'We got whopped 5-0.' It is a noun too: 'she gave the door a whop with her hand.' This is a country-flavoured, old-fashioned, mostly American word. You hear it in speech, in old stories, in the South of the United States; you will almost never see it in a newspaper or a textbook. In Taiwan you are far more likely to meet it in a novel or a film than in real conversation. Spelling wanders, because it is mostly a spoken word: whop, whup, whomp, wallop all live in the same neighbourhood. Your dictionary points this one at 'whup', and they really are the same idea. The most important thing about whop for a learner is not the verb at all — it is that this word is the parent of a word you will actually use: whopping, meaning 'surprisingly big'. Something so big it hits you.

重擊、揍（老式、美國鄉土口語）；痛宰（比賽大勝）