The Collaborative International Dictionary of English v.0.48:

Hospitalize \Hos"pi*tal*ize\, v. t.
   1. (Med.) To render (a building) unfit for habitation, by
      long continued use as a hospital. [Archaic]
      [1913 Webster]

   2. To place (a person) in a hospital in order to receive
      medical treatment, observation, or for rest.

   Syn: hospitalise.
        [PJC]

WordNet (r) 3.0 (2006):

hospitalize
    v 1: admit into a hospital; "Mother had to be hospitalized
         because her blood pressure was too high" [syn:
         hospitalize, hospitalise]