καταπῡγ-ων · katapyg-ōn — LSJ
male passive homosexual, sts. loosely as a term of abuse [Supp.], Id. Ach. 79, al., Luc. Tim. 22, Alciphr. 3.45, etc.; ὦ κατάπυγον Ar. Th. 200.--The oblique cases are sts. wrongly written -πύγωνος, cf. Hdn. Gr. 2.725: irreg. Comp. -πυγωνέστερος (metri gr.) Ar. Lys. 776.
in Att., the middle finger (used in an obscene gesture), Poll. 2.184.