υπερθύριον

From LSJ

ποταμῷ γὰρ οὐκ ἔστιν ἐμβῆναι δὶς τῷ αὐτῷ → it is impossible to step twice in the same river, you cannot step twice into the same rivers

Source

Greek Monolingual

τὸ, Α
το υπέρθυρο.
[ΕΤΥΜΟΛ. < ὑπερ- + -θύριον (< θύρα), πρβλ. παρα-θύρι(ον)].