The Collaborative International Dictionary of English v.0.48:
Trichloride \Tri*chlo"ride\, n. [Pref. tri- + chloride.] (Chem.) A chloride having three atoms of chlorine in the molecule. [1913 Webster]WordNet (r) 3.0 (2006):
trichloride n 1: any compound containing three chlorine atoms in each molecule