Lewis & Short

fētōsus (foet-), a, um, adj. [2. fetus], prolific (late Lat.): oves, Vulg. Psa. 143, 13.
Also fētŭōsus, a, um: Lea, Hier. adv. Jovin. 1, 19 (al. fetosa); id. Galat. 4, 27.