a. [ L. ultroneus, from ultro to the further side, on his part, of one's own accord. See Ultra-. ] Spontaneous; voluntary. [ Obs. ] Jer. Taylor. -- Ul*tro"ne*ous*ly, adv. [Obs.] -- Ul*tro"ne*ous*ness, n. [ Obs. ] [ 1913 Webster ]