rotundatio
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)
rŏtundātĭo: ōnis, f. rotundo,
I a making round, a rounding: linea rotundationis, i. e. the circumference, Vitr. 1, 6 fin.; 3, 1; 10, 11.
