[tī′tā·nē·əm ¦te·trə′klȯr‚īd] (inorganic chemistry) TiCl4 A colorless, toxic liquid soluble in water, fumes when exposed to moist air, boils at 136°C; used to make titanium and titanium salts, as a dye mordant and polymerization catalyst, and in smoke screens and pigments. Also known as titanic chloride.