ἆρον

From LSJ

Δελφῖνα νήχεσθαι διδάσκεις: ἐπὶ τῶν ἐν ἐκείνοις τινὰ παιδοτριβούντων, ἐν οἷς ἤσκηται → Teaching dolphins to swim: is applied to those who are teaching something among people who are already well versed in it

Source

French (Bailly abrégé)

impér. ao. de αἴρω.

Greek Monotonic

ἆρον: προστ. αορ. αʹ του αἴρω.

Russian (Dvoretsky)

ἆρον: imper. aor. к αἴρω.