Trivalent \Triv"a*lent\, a. [Pref. tri- + L. valens, -entis, p. pr. See Valence.]

(Chem.) Having a valence of three; capable of being combined with, substituted for, or compared with, three atoms of hydrogen; -- said of triad atoms or radicals; thus, nitrogen is trivalent in ammonia.

Source: Webster's Revised Unabridged Dictionary (1913)