Source : Webster's Revised Unabridged Dictionary (1913)

Whap \Whap\, Whop \Whop\, v. t. [imp. & p. p. {Whapped}; p. pr.
   & vb. n. {Whapping}.]
   To beat or strike.

Whapping \Whap"ping\, Whopping \Whop"ping\, a.
   Very large; monstrous; astonishing; as, a whapping story.
   [Colloq.]

Source : WordNet®

whapping
     See {whap}

whap
     v : hit hard [syn: {sock}, {bop}, {whop}, {bonk}, {bash}]
     [also: {whapping}, {whapped}]