τένθω
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)
A v. τένδω. τέννει· στένει, βρύχεται, Hsch. τέννος· στέφανος ἐλάϊνος ἐρίῳ πεπλεγμένος, Id.
German (Pape)
[Seite 1091] att. = τένδω, VLL.