Source : Webster's Revised Unabridged Dictionary (1913)

Unsubstantialize \Un`sub*stan"tial*ize\, v. t. [1st pref. un- +
   substantialize.]
   To make unsubstantial. [R.]

Source : WordNet®

unsubstantialize
     v : render immaterial or incorporeal [syn: {immaterialize}, {immaterialise},
          {unsubstantialise}]