Source : Webster's Revised Unabridged Dictionary (1913)

Piratical \Pi*rat"ic*al\, a. [L. piraticus, Gr. ?: cf. F.
   piratique.]
   Of or pertaining to a pirate; acquired by, or practicing,
   piracy; as, a piratical undertaking. ``Piratical printers.''
   --Pope. -- {Pi*rat"ic*al*ly}, adv.

Source : WordNet®

piratical
     adj 1: characteristic of pirates; "piratical attackers"
     2: characteristic of piracy; "piratical editions of my book"