Lewis & Short

urvo (urbo), āre, v. n. [urvum], to plough round, mark out with a plough: urvat, Ennius in Andromedā significat circumdat, ab eo sulco, qui fit in urbe condendā urvo aratriAit autem: Circum sese urvat ad pedes, etc., Fest. p. 375 Müll. N. cr. (Trag. v. 141 Vahl.); cf.: urvare est aratro definire, Dig. 50, 16, 239, § 6.