ὕπεας

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

Russian (Dvoretsky)

ὕπεας: и ὕπεαρ, атт. * ὄπεας, ατος τό шило Her.

German (Pape)

τό, f.l. statt ὄπεας Her. 4.70.