a. [ L. ternarius, fr. terni. See Tern, a. ] 1. Proceeding by threes; consisting of three; as, the ternary number was anciently esteemed a symbol of perfection, and held in great veneration. [ 1913 Webster ]
2. (Chem.) Containing, or consisting of, three different parts, as elements, atoms, groups, or radicals, which are regarded as having different functions or relations in the molecule; thus, sodic hydroxide, NaOH, is a ternary compound. [ 1913 Webster ]