Webster’s Revised Unabridged Dictionary · 1913
Trivalent
Triv′a·lent (·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.