ὀρθὴ γωνία

From LSJ

εἰ ἔρρωσαι καὶ ἐν τοῖς ἄλλοις ἀλύπως ἀπαλλάσσεις → if you are well and in other respects are getting on without annoyance

Source

Greek > English (Woodhouse)

right angle