Source : Webster's Revised Unabridged Dictionary (1913)

Medicine \Med"i*cine\, n. [L. medicina (sc. ars), fr. medicinus
   medical, fr. medicus: cf. F. m['e]decine. See {Medical}.]
   1. The science which relates to the prevention, cure, or
      alleviation of disease.

   2. Any substance administered in the treatment of disease; a
      remedial agent; a remedy; physic.

            By medicine, life may be prolonged.   --Shak.

   3. A philter or love potion. [Obs.] --Shak.

   4. [F. m['e]decin.] A physician. [Obs.] --Shak.

   {Medicine bag}, a charm; -- so called among the North
      American Indians, or in works relating to them.

   {Medicine man} (among the North American Indians), a person
      who professes to cure sickness, drive away evil spirits,
      and regulate the weather by the arts of magic.

   {Medicine seal}, a small gem or paste engraved with reversed
      characters, to serve as a seal. Such seals were used by
      Roman physicians to stamp the names of their medicines.

Source : WordNet®

medicine man
     n : a Native American shaman