|thalō+ noun
Etymology: International Scientific Vocabulary phthal- + cyanine
1. or phthalocyanine blue G : a bright greenish blue crystalline compound C 32 H 18 N 8 related to porphin — called also metal-free phthalocyanine ; see dye table I (under Pigment Blue 16 )
2. : any of various derivatives of phthalocyanine that in the case of the metal derivatives are brillant fast blue to green dyes or pigments made usually by heating phthalonitrile with a metal (as copper powder) or metallic salt