[uni.tar.i.an] n [NL unitarius, fr. L unitas unity] (1687) 1 a often cap: one who believes that the deity exists only in one person b cap: a member of a denomination that stresses individual freedom of belief, the free use of reason in religion, a united world community, and liberal social action
2: an advocate of unity or a unitary system -- unitarian adj, often cap -- uni.tar.i.an.ism n, often cap