R / rēfrāgātor
noun

rēfrāgātor

gen. rē^frāgātōris · gender masculine · decl. 3rd
an opponent; adversary
an opponent, adversary: Ciceronis, Ascon. ad Or. in Tog. Cand. (p. 83 Orell.); Tert. adv. Gnost. 1.