sundog

from WordNet (r) 3.0 (2006)

sundog
    n 1: a bright spot on the parhelic circle; caused by diffraction
         by ice crystals; "two or more parhelia are usually seen at
         once" [syn: {parhelion}, {mock sun}, {sundog}]

from The Collaborative International Dictionary of English v.0.48

Sundog \Sun"dog`\, n. (Meteorol.)
   1. A luminous spot occasionally seen a few degrees from the
      sun, supposed to be formed by the intersection of two or
      more halos, or in a manner similar to that of halos.
      [1913 Webster]

   2. A fragmentary rainbow; a small rainbow near the horizon;
      -- called also {dog} and {weathergaw}.
      [Webster 1913 Suppl.]