τᾄτιον
From LSJ
εὖτ' ἂν ὑπὸ τοῦ κακοῦ κτεινέωνται → when the disease is proceeding towards a fatal termination
German (Pape)
[Seite 1073] att. zsgzgn statt τὸ αἴτιον, Ar. Th. 549.
Greek (Liddell-Scott)
τᾄτιον: Ἀττ. κρᾶσις, ἀντὶ τὸ αἴτιον, Ἀριστοφ. Θεσμ. 549.