πυριφλεγέθων
From LSJ
ὁποία δ' ἦν αὕτη ἡ παίδευσις δύναταί τις γιγνώσκειν διάλογόν τινα τοῦ Πλάτωνος σκοπῶν → It's possible to find out what kind of education that was by examining one of Plato's dialogues
English (LSJ)
ουσα, ον,
A blazing like fire, ἔσοπτρον Agesianax ap.Plu.2.921b. II pr. n. Pyriphlegethon, one of the rivers of hell, Od.10.513, Pl.Phd. 114a.