The Collaborative International Dictionary of English v.0.48:

Garrote \Gar*rote"\, n. [Sp. garrote, from garra claw, talon, of
   Celtic origin; cf. Armor. & W. gar leg, ham, shank. Cf.
   Garrot stick, Garter.]
   A Spanish mode of execution by strangulation, with an iron
   collar affixed to a post and tightened by a screw until life
   become extinct.
   [1913 Webster]

   2. The instrument by means of which the garrote[1] is
      inflicted.

   Syn: garrote, garotte, iron collar.
        [1913 Webster + WordNet 1.5]

   3. Hence: A short length of rope or other instrument used to
      strangle a person.
      [PJC]

The Collaborative International Dictionary of English v.0.48:

Garrote \Gar*rote"\, v. t. [imp. & p. p. Garroted; p. pr. &
   vb. n. Garroting.]
   To strangle with the garrote; hence, to seize by the throat,
   from behind, with a view to strangle and rob.
   [1913 Webster]

WordNet (r) 3.0 (2006):

garrote
    n 1: an instrument of execution for execution by strangulation
         [syn: garrote, garotte, garrotte, iron collar]
    v 1: strangle with an iron collar; "people were garrotted during
         the Inquisition in Spain" [syn: garrote, garrotte,
         garotte, scrag]