The Collaborative International Dictionary of English v.0.48:

Gorget \Gor"get\, n. [OF. gorgete, dim. of gorge throat. See
   Gorge, n.]
   1. A piece of armor, whether of chain mail or of plate,
      defending the throat and upper part of the breast, and
      forming a part of the double breastplate of the 14th
      century.
      [1913 Webster]

   2. A piece of plate armor covering the same parts and worn
      over the buff coat in the 17th century, and without other
      steel armor.
      [1913 Webster]

            Unfix the gorget's iron clasp.        --Sir W.
                                                  Scott.
      [1913 Webster]

   3. A small ornamental plate, usually crescent-shaped, and of
      gilded copper, formerly hung around the neck of officers
      in full uniform in some modern armies.
      [1913 Webster]

   4. A ruff worn by women. [Obs.]
      [1913 Webster]

   5. (Surg.)
      (a) A cutting instrument used in lithotomy.
      (b) A grooved instrunent used in performing various
          operations; -- called also blunt gorget.
          --Dunglison.
          [1913 Webster]

   6. (Zool.) A crescent-shaped, colored patch on the neck of a
      bird or mammal.
      [1913 Webster]

   Gorget hummer (Zool.), a humming bird of the genus
      Trochilus. See Rubythroat.
      [1913 Webster]

WordNet (r) 3.0 (2006):

gorget
    n 1: armor plate that protects the neck