Definition of paddywhack in English:

paddywhack

Pronunciation /ˈpadɪwak/

noun

(also paddywack)
  • 1 informal, derogatory An Irishman.

  • 2US informal, rare = "paddy".

  • 3 informal A severe beating; a violent blow. Now chiefly nursery.

    Sometimes with allusion to the chorus of the folk song This Old Man.

Origin

Late 18th century. Apparently from paddy + whack, although the semantic motivation for the compound is unclear.