The Collaborative International Dictionary of English v.0.48:

Colorimeter \Col`or*im"e*ter\, n. [Color + -meter: cf. F.
   colorim[`e]tre.]
   An instrument for measuring the depth of the color of
   anything, especially of a liquid, by comparison with a
   standard liquid.
   [1913 Webster]

WordNet (r) 3.0 (2006):

colorimeter
    n 1: a measuring instrument used in colorimetric analysis to
         determine the quantity of a substance from the color it
         yields with specific reagents [syn: colorimeter,
         tintometer]