Source : Webster's Revised Unabridged Dictionary (1913)

Visualize \Vis"u*al*ize\, v. t.
   To make visual, or visible; to see in fancy. [Written also
   {visualise}.]

         No one who has not seen them [glaciers] can possibly
         visualize them.                          --Lubbock.

Source : WordNet®

visualise
     v 1: view the outline of by means of an X-ray; "The radiologist
          can visualize the cancerous liver" [syn: {visualize}]
     2: for a mental picture of something that is invisible or
        abstract; "Mathematicians often visualize" [syn: {visualize}]
     3: imagine; conceive of; see in one's mind; "I can't see him on
        horseback!"; "I can see what will happen"; "I can see a
        risk in this strategy" [syn: {visualize}, {envision}, {project},
         {fancy}, {see}, {figure}, {picture}, {image}]
     4: make visible; "With this machine, ultrasound can be
        visualized" [syn: {visualize}]