|tər+ noun
Etymology: International Scientific Vocabulary ter- + phenyl
: any of three isomeric crystalline hydrocarbons C 6 H 5 C 6 H 4 C 6 H 5 that contain three benzene rings linked in ortho, meta, and para positions, that are obtained usually along with biphenyl from benzene, and that are used chiefly as industrial heat transfer media ; also : a mixture of two or all three of these hydrocarbons