Thwack

[imp. & p. p. THWACKED (thwăkt); p. pr. & vb. n. THWACKING.] [O. Eng. thacce; A-S. thaccian, to touch gently, to stroke. Cf. WHACK.] To strike with something flat or heavy; to bang; to beat or thrash; to thump.

n. A heavy blow with something flat or heavy; a thump.

With many a stiff thwack, many a bang, Hard crab-tree and old iron rang. Hudibras.