D defs.my
Entry 3 senses · 2 variants Webster, 1913

Thwack

/(thwăk)/ · IPA /θwæk/
01 v. t. To strike with something flat or heavy; to bang, or thrash: to thump.
imp. & p. p. Thwacked; p. pr. & vb. n. Thwacking
  1. 1.
    To strike with something flat or heavy; to bang, or thrash: to thump.
  2. 2.
    To fill to overflow.[Obs.]
02 n. A heavy blow with something flat or heavy; a thump.
  1. 1.
    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.