κάρτος
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)
εος, τό, Ep. and Dor. for κράτος (for which it is v.l. in Hdt.8.2),
A strength, vigour, κάρτεϊ καὶ σθένεϊ σφετέρῳ Il.17.322; κάρτος τε βίη τε Od.6.197; violence, force, κάρτεϊ νικήσας πατέρα Hes.Th. 73; κάρτεϊ, = βίᾳ, Leg.Gort.2.3, al.
