Polychromate \Pol`y*chro"mate\, n. [See {Polychromic}.] (Chem.) A salt of a polychromic acid. Polychromate \Pol`y*chro"mate\, n. [See {Polychromatic}.] (Chem.) A compound which exhibits, or from which may be prepared, a variety of colors, as certain solutions derived from vegetables, which display colors by fluorescence.