The Collaborative International Dictionary of English v.0.48:

Hospital \Hos"pi*tal\, n. [OF. hospital, ospital, F. h[^o]pital,
   LL. hospitale (or perh. E. hospital is directly from the Late
   Latin), from L. hospitalis relating to a guest, hospitalia
   apartments for guests, fr. hospes guest. See Host a
   landlord, and cf. Hostel, Hotel, Spital.]
   1. A place for shelter or entertainment; an inn. [Obs.]
      --Spenser.
      [1913 Webster]

   2. A building in which the sick, injured, or infirm are
      received and treated; a public or private institution
      founded for reception and cure, or for the refuge, of
      persons diseased in body or mind, or disabled, infirm, or
      dependent, and in which they are treated either at their
      own expense, or more often by charity in whole or in part;
      a tent, building, or other place where the sick or wounded
      of an army cared for.
      [1913 Webster]

   Hospital ship, a vessel fitted up for a floating hospital.


   Hospital Sunday, a Sunday set apart for simultaneous
      contribution in churches to hospitals; as, the London
      Hospital Sunday.
      [1913 Webster]

WordNet (r) 3.0 (2006):

hospital ship
    n 1: a ship built to serve as a hospital; used for wounded in
         wartime