1) Chemical group 2) Group 3) Radical 
Compare with auxochrome. A group or substructure on a molecule that is responsible for the absorption of light.
A chromophore is the part of a molecule responsible for its color. The color arises when a molecule absorbs certain wavelengths of visible light and transmits or reflects others. The chromophore is a region in the molecule where the energy difference between two different molecular orbitals falls within the range of the visible spectrum. Visible l...
• (n.) Any chemical group or residue (as NO2; N2; or O2) which imparts some decided color to the compound of which it is an ingredient.
a group of atoms and electrons forming part of an organic molecule that causes it to be coloured.[3 related articles]
The part (atom or group of atoms) of a molecular entity in which the electronic transition responsible for a given spectral band is approximately localized. The term arose in the dyestuff industry, referring originally to the groupings in the molecule that are responsible for the dye's colour. WITT (1876).
functional groups with characteristic optical absorptions or the molecules which contain them.
The part of a visibly coloured molecule responsible for light absorption over a range of wavelengths thus giving rise to the colour. By extension the term may be applied to UV or IR absorbing parts of molecules. Do not confuse with chromatophores. ... (18 Nov 1997) ... 
(kro´mo-for) any chemical group whose presence gives a decided color to a compound and that unites with certain other groups (auxochromes) to form dyes; called also color radical.
The part of a visibly coloured molecule responsible for light absorption over a range of wavelengths thus giving rise to the colour. By extension the term may be applied to UV or IR absorbing parts of molecules. Do not confuse with chromatophores.
Chro'mo·phore noun [ Greek ... color + ... to bear.] (Chemistry) Any chemical group or residue (as NO 2 ; N 2 ; or O 2 ) which imparts some decided color to the compound of which it is an ingredient. 
Type: Term Pronunciation: krō′mō-fōr Definitions: 1. The atomic grouping on which the color of a substance depends. 2. A target tissue for laser light therapy; absorption wavelength of tissue determines choice of laser wavelength. Common dermal chromophores include hemoglobin, oxyhemoglobin, collagen, beta-carotene, and melanin...
[n] - the chemical group that gives color to a molecule
A group or substructure on a molecule that is responsible for the absorption of light. 
noun the chemical group that gives color to a molecule
any chemical group that produces color in a compound, as the azo group −N=N−.