Πρωταγόρειος
From LSJ
ὥστε ὁ βίος, ὢν καὶ νῦν χαλεπός, εἰς τὸν χρόνον ἐκεῖνον ἀβίωτος γίγνοιτ' ἂν τὸ παράπαν → and so life, which is hard enough now, would then become absolutely unendurable
English (LSJ)
α, ον, Protagoran, of Protagoras, μέτρον Pl.Tht.162c; μῦθος ib. 164d.
Greek (Liddell-Scott)
Πρωτᾰγόρειος: -α, -ον, ὁ εἰς τὸν Πρωταγόραν ἀνήκων, μῦθος Πλάτ. Θεαίτ. 126C, 164D.
Russian (Dvoretsky)
Πρωτᾰγόρειος: протагоров(ский).