ὑπόστρωμα
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)
ατος, τό,
A that which is spread under, bedding, litter, ἵππου X.Eq.5.2, cf. Dsc.1.103, Peripl.M.Rubr.65.
