πεφνέμεν
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
Russian (Dvoretsky)
πεφνέμεν: эп. inf. = * πεφνεῖν.
Dutch (Woordenboekgrieks.nl)
πεφνέμεν ep. inf. aor. act. van θείνω.
