Source : Webster's Revised Unabridged Dictionary (1913)

Indigestion \In`di*ges"tion\ (?; 106), n. [L. indigestio: cf. F.
   indigestion. See {In-} not, and {Digest}.]
   Lack of proper digestive action; a failure of the normal
   changes which food should undergo in the alimentary canal;
   dyspepsia; incomplete or difficult digestion.

Source : WordNet®

indigestion
     n : a disorder of digestive function characterized by discomfort
         or heartburn or nausea [syn: {dyspepsia}, {stomach upset},
          {upset stomach}]