Source : Webster's Revised Unabridged Dictionary (1913)

Zodiacal \Zo*di"a*cal\, a. [Cf. F. zodiacal.] (Astron.)
   Of or pertaining to the zodiac; situated within the zodiac;
   as, the zodiacal planets.

   {Zodiacal light}, a luminous tract of the sky, of an
      elongated, triangular figure, lying near the ecliptic, its
      base being on the horizon, and its apex at varying
      altitudes. It is to be seen only in the evening, after
      twilight, and in the morning before dawn. It is supposed
      to be due to sunlight reflected from multitudes of
      meteoroids revolving about the sun nearly in the plane of
      the ecliptic.

Source : WordNet®

zodiacal light
     n : a luminous tract in the sky; a reflection of sunlight from
         cosmic dust in the plane of the ecliptic; visible just
         before sunrise and just after sunset