The Collaborative International Dictionary of English v.0.48:

dollhouse \dollhouse\ n.
   1. a house so small that it is likened to a child's
      dollhouse. Sometimes used in reference to a small house
      with especially elaborate exterior decoration.
      [WordNet 1.5 +PJC]

   2. a small model of a house used as a toy by children,
      usually including miniature furniture and other objects
      that can be arranged inside it as the would be in a real
      house.
      [WordNet 1.5 +PJC]

WordNet (r) 3.0 (2006):

dollhouse
    n 1: a house so small that it is likened to a child's plaything
         [syn: dollhouse, doll's house]
    2: a small model of a house used as a toy by children [syn:
       dollhouse, doll's house]