νίψαι

From LSJ

πάντα χωρεῖ καὶ οὐδὲν μένει καὶ δὶς ἐς τὸν αὐτὸν ποταμὸν οὐκ ἂν ἐμβαίης → all things move and nothing remains still, and you cannot step twice into the same stream

Source

Greek Monotonic

νίψαι: απαρ. αορ. αʹ του νίζω· νίψω, μέλ.