Source : Webster's Revised Unabridged Dictionary (1913)

Nitro- \Ni"tro-\
   1. A combining form or an adjective denoting the presence of
      niter.

   2. (Chem.) A combining form (used also adjectively)
      designating certain compounds of nitrogen or of its acids,
      as nitrohydrochloric, nitrocalcite; also, designating the
      group or radical {NO2}, or its compounds, as nitrobenzene.

   {Nitro group}, the radical {NO2}; -- called also {nitroxyl}.

Nitro- \Ni"tro-\
   1. A combining form or an adjective denoting the presence of
      niter.

   2. (Chem.) A combining form (used also adjectively)
      designating certain compounds of nitrogen or of its acids,
      as nitrohydrochloric, nitrocalcite; also, designating the
      group or radical {NO2}, or its compounds, as nitrobenzene.

   {Nitro group}, the radical {NO2}; -- called also {nitroxyl}.

Nitroxyl \Ni*trox"yl\, n. [Nitro- + oxygen + -yl.] (Chem.)
   The group {NO2}, usually called the {nitro group}.

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.