ἀντίπτωσις
From LSJ
λέγεις, ἃ δὲ λέγεις ἕνεκα τοῦ λαβεῖν λέγεις → you speak, but you say what you say for the sake of gain (Menander, fr. 776)
English (LSJ)
εως, ἡ,
A opposition, resistance, Hp.Decent.3 (pl.). II Gramm., interchange of cases, Priscian. Inst.17.155, Sch.Ar.V.135.
German (Pape)
[Seite 260] ἡ, Gegenfall, bei den Gramm. Setzung eines Casus anstatt eines anderen.