Source : Webster's Revised Unabridged Dictionary (1913)

Ergot \Er"got\, n. [F. ergot, argot, lit., a spur.]
   1. A diseased condition of rye and other cereals, in which
      the grains become black, and often spur-shaped. It is
      caused by a parasitic fungus, {Claviceps purpurea}.

   2. The mycelium or spawn of this fungus infecting grains of
      rye and wheat. It is a powerful remedial agent, and also a
      dangerous poison, and is used as a means of hastening
      childbirth, and to arrest bleeding.

   3. (Far.) A stub, like soft horn, about the size of a
      chestnut, situated behind and below the pastern joint.

   4. (Anat.) See 2d {Calcar}, 3
      (b) .

Source : WordNet®

ergot
     n 1: a plant disease caused by the ergot fungus
     2: a fungus that infects various cereal plants forming compact
        black masses of branching filaments that replace many
        grains of the plant; source of medicinally important
        alkaloids and of lysergic acid [syn: {Claviceps purpurea}]