πλατύστομος
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
English (LSJ)
ον,
A wide-mouthed, λέβης, χύτρα, ἀγγεῖον, Dsc.1.30, Damocr. ap. Gal. 13.40, Gp.9.24.1; of a cupping instrument, Sor.1.50.
