diremptus
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
Latin > English (Lewis & Short)
dĭremptus: a, um, Part., from dirimo.
dĭremptus: ūs, m. dirimo,
I a separation, Cic. Tusc. 1, 29, 71.