The Collaborative International Dictionary of English v.0.48:

Fumigation \Fum`iga"tion\, n. [Cf. F. fumigation.]
   [1913 Webster]
   1. The act of fumigating, or applying smoke or vapor, as for
      disinfection.
      [1913 Webster]

   2. Vapor raised in the process of fumigating.
      [1913 Webster]

WordNet (r) 3.0 (2006):

fumigation
    n 1: the application of a gas or smoke to something for the
         purpose of disinfecting it

Moby Thesaurus II by Grady Ward, 1.0:

29 Moby Thesaurus words for "fumigation":
   aeration, aerification, antisepsis, atomization, decontamination,
   deodorization, deodorizing, disinfection, disinfestation,
   distillation, etherealization, etherification, evaporation,
   exhalation, flash pasteurization, fluidization, fractionation,
   gasification, hygenics, hygiene, pasteurization, sanitation,
   smoking, steaming, sterilization, sublimation, vaporization,
   ventilation, volatilization