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.

Visualize \Vis"u*al*ize\, v. i.
   To form a mental image of something not present before the
   eye at the time.

Source : WordNet®

visualize
     v 1: 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: {visualise}, {envision}, {project},
           {fancy}, {see}, {figure}, {picture}, {image}]
     2: view the outline of by means of an X-ray; "The radiologist
        can visualize the cancerous liver" [syn: {visualise}]
     3: for a mental picture of something that is invisible or
        abstract; "Mathematicians often visualize" [syn: {visualise}]
     4: make visible; "With this machine, ultrasound can be
        visualized" [syn: {visualise}]