The Collaborative International Dictionary of English v.0.48:

Chromatic \Chro*mat"ic\, a. [L. chromaticus, Gr. ?, suited for
   color, fr. ?, ?, color; akin to ? color, ? skin, color of the
   skin.]
   1. Relating to color, or to colors.
      [1913 Webster]

   2. (Mus.) Proceeding by the smaller intervals (half steps or
      semitones) of the scale, instead of the regular intervals
      of the diatonic scale.
      [1913 Webster]

   Note: The intermediate tones were formerly written and
         printed in colors.
         [1913 Webster]

   Chromatic aberration. (Opt.) See Aberration, 4.

   Chromatic printing, printing from type or blocks covered
      with inks of various colors.

   Chromatic scale (Mus.), the scale consisting of thirteen
      tones, including the eight scale tones and the five
      intermediate tones.
      [1913 Webster]

WordNet (r) 3.0 (2006):

chromatic scale
    n 1: a 12-note scale including all the semitones of the octave