μαστρυλλεῖον
From LSJ
κάμψαι διαύλου θάτερον κῶλον πάλιν → bend back along the second turn of the race, turning the bend and coming back for the second leg of the double run, run the homeward course, retrace one's steps
English (LSJ)
μαστρ-ύλλιον, f.ll. for ματρυλεῖον (q.v.).
Greek (Liddell-Scott)
μαστρυλλεῖον: μαστρύλλιον, ἡμαρτημ. γραφὴ ἀντὶ ματρυλεῖον, ὃ ἴδε.