Abridged from Harpokration s.v.; the headword, there and again here, is accusative plural.
The entry originated in ancient comment on Aeschines 1.59 (web address 1). There is a helpful note on the Aeschines passage in the Loeb edition; see also LSJ s.v. a)kakou/rghtos (web address 2).
Dice were, from an unknown time onwards, shaken and thrown from a "tower" (pu/rgos: Greek Anthology 9.373; cf. tau 7, pi 1384), fluted in such a way as to prevent any attempt to cheat in throwing (Martial 14.16). At least some players threw their dice from above their heads (Greek Anthology 5.24; cf. kappa 2602 note [4]), perhaps in allusion to the gods above and the proverb, "For only the dice of a god always fall well" (Sophocles fr. 895P = 809N; cf. alpha 607).