Lewis & Short

dēclāmātōrĭus, a, um, adj. [declamator], of or belonging to the exercise of speaking, declamatory, rhetorical (good prose): opus, Cic. de Or. 1, 16 fin.: illo genere duci et delectari, id. Q. Fr. 3, 3 fin.; ef.: genus dicendi, Quint. 2, 10, 9: consuetudo, id. 5, 13, 46: licentia, id. 8, 3, 76: res, id. 4, 2, 128: studium, Tac. Or. 14.
Hence, adv.: dēclāmātōriē, in a rhetorical manner (late Lat.), Hieron. al.