The Collaborative International Dictionary of English v.0.48:

Dematerialize \De`ma*te"ri*al*ize\, v. t.
   To deprive of material or physical qualities or
   characteristics.
   [1913 Webster]

         Dematerializing matter by stripping it of everything
         which . . . has distinguished matter.    --Milman.
   [1913 Webster]

WordNet (r) 3.0 (2006):

dematerialize
    v 1: become immaterial; disappear [syn: dematerialize,
         dematerialise] [ant: happen, materialise,
         materialize]