Source : Webster's Revised Unabridged Dictionary (1913)

Chromophore \Chro"mo*phore\, n. [Gr. ? color + ? to bear.]
   (Chem.)
   Any chemical group or residue (as {NO2}; {N2}; or {O2}) which
   imparts some decided color to the compound of which it is an
   ingredient.

Source : WordNet®

chromophore
     n : the chemical group that gives color to a molecule