ἀθεμιτογαμέω
From LSJ
ἔκστασίς τίς ἐστιν ἐν τῇ γενέσει τὸ παρὰ φύσιν τοῦ κατὰ φύσιν → what is contrary to nature is any developmental aberration from what is in accord with nature (Aristotle, On the Heavens 286a19)
Spanish (DGE)
contraer matrimonio ilícito, contraer matrimonio incestuoso Eus.PE 6.10.15.