This article deals with ambegna bos, lexical unit, which occurs in Varro’s work De lingua Latina (7.31) as a sample of the augurs’ professional language. As Varro explained it, its usage means the participation of the augurs in public ritual of animal sacrifice, which was controlled by the pontifices. The augurs participated in the event as they watched the animals’ behavior and interpreted it selecting those which were to be sacrificed. Their actions guaranteed the favorable acceptance of the victim by the gods. Thus one can argue that the augurs took part in the preparation to public ritual of animal sacrifice according to their primordial duty to interpret the omens coming from the gods, i.e. they performed auguries. The intersection of the pontifices’ and the augurs’ duties in that reflects the strive of the Roman aristocracy not to admit any concentration of power (including the religious one) in the same hands in the course of establishing the new political regime (res publica), which replaced the previous regime of royal power (the regnum). Thus, information preserved by Varro dates back to the most ancient layer of the Roman sacral tradition.