Source : Webster's Revised Unabridged Dictionary (1913)

Comma \Com"ma\, n. [L. comma part of a sentence, comma, Gr. ?
   clause, fr. ? to cut off. Cf. {Capon}.]
   1. A character or point [,] marking the smallest divisions of
      a sentence, written or printed.

   2. (Mus.) A small interval (the difference between a major
      and minor half step), seldom used except by tuners.

   {Comma bacillus} (Physiol.), a variety of bacillus shaped
      like a comma, found in the intestines of patients
      suffering from cholera. It is considered by some as having
      a special relation to the disease; -- called also {cholera
      bacillus}.

   {Comma butterfly} (Zo["o]l.), an American butterfly ({Grapta
      comma}), having a white comma-shaped marking on the under
      side of the wings.

Source : WordNet®

comma butterfly
     n : anglewing butterfly with a comma-shaped mark on the
         underside of each hind wing [syn: {comma}, {Polygonia
         comma}]