wal·lop / ˈwäləp/ inf. • v. (-loped, -lop·ing) [tr.] strike or hit (someone or something) very hard: they walloped the back of his head with a stick | fig. they were tired of getting walloped with income taxes. ∎ heavily defeat (an opponent).• n. a heavy blow or punch. ∎ [in sing.] fig. a potent effect: the script packs a wallop.DERIVATIVES: wal·lop·er n.