col·or·im·e·ter 
(kŭl′ə-rĭmĭ-tər)
(kŭl′ə-rĭmĭ-tər)n.
1. Any of various instruments used to determine or specify colors, as by comparison with spectroscopic or visual standards.
2. An instrument that measures the concentration of a known constituent of a solution by comparison with colors of standard solutions of that constituent.
col′or·i·metric (-ər-ə-mĕtrĭk) adj.
col′or·i·metri·cal·ly adv.
col′or·ime·try n.