πετεύριον
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)
τό, Dim. of πέτευρον IV, A small notice-board, Jahresh.13 Beibl.23(Erythrae, iv B. C.).
Greek Monolingual
τὸ, Α πέτευρον
μικρή πινακίδα, σημειωματάριο.