The Collaborative International Dictionary of English v.0.48:

Stateroom \State"room`\ (st[=a]t"r[=oo]m`), n.
   1. A magnificent room in a palace or great house.
      [1913 Webster]

   2. A small apartment for lodging or sleeping in the cabin, or
      on the deck, of a vessel; also, a somewhat similar
      apartment in a railway sleeping car.
      [1913 Webster]

WordNet (r) 3.0 (2006):

stateroom
    n 1: a guest cabin