The Collaborative International Dictionary of English v.0.48:

Cautery \Cau"ter*y\, n.; pl. Cauteries. [L. cauterium, Gr. ?.
   See Cauter.]
   1. (Med.) A burning or searing, as of morbid flesh, with a
      hot iron, or by application of a caustic that will burn,
      corrode, or destroy animal tissue.
      [1913 Webster]

   2. The iron of other agent in cauterizing.
      [1913 Webster]

   Actual cautery, a substance or agent (as a hot iron) which
      cauterizes or sears by actual heat; or the burning so
      effected.

   Potential cautery, a substance which cauterizes by chemical
      action; as, lunar caustic; also, the cauterizing produced
      by such substance.
      [1913 Webster]

WordNet (r) 3.0 (2006):

cautery
    n 1: an instrument or substance used to destroy tissue for
         medical reasons (eg removal of a wart) by burning it with a
         hot iron or an electric current or a caustic or by freezing
         it [syn: cautery, cauterant]
    2: the act of coagulating blood and destroying tissue with a hot
       iron or caustic agent or by freezing [syn: cautery,
       cauterization, cauterisation]