The Collaborative International Dictionary of English v.0.48:

decontamination \decontamination\ n.
   The removal of contaminants; as, the decontamination of a
   room after a spill of radioactive materials.
   [WordNet 1.5 +PJC] decor

WordNet (r) 3.0 (2006):

decontamination
    n 1: the removal of contaminants [ant: contamination,
         pollution]

Moby Thesaurus II by Grady Ward, 1.0:

44 Moby Thesaurus words for "decontamination":
   activity, allowance, antisepsis, artificial radioactivity, color,
   contamination, curiage, disinfection, disinfestation,
   extenuating circumstances, extenuation, extenuative, fallout,
   flash pasteurization, fumigation, gilding, gloss, half-life,
   hygenics, hygiene, mitigation, natural radioactivity,
   nuclear radiation, palliation, palliative, pasteurization,
   qualification, radiant energy, radiation, radioactive radiation,
   radioactivity, radiocarbon dating, radiolucency, radiopacity,
   radiosensibility, radiosensitivity, sanitation, saturation point,
   softening, specific activity, sterilization, varnish, whitewash,
   whitewashing