The Collaborative International Dictionary of English v.0.48:

Diorama \Di`o*ra"ma\, n. [Gr. ? to see through; ? = dia` through
   + ? to see; cf. ? that which is seen, a sight: cf. F.
   diorama. Cf. Panorama.]
   1. A mode of scenic representation, invented by Daguerre and
      Bouton, in which a painting is seen from a distance
      through a large opening. By a combination of transparent
      and opaque painting, and of transmitted and reflected
      light, and by contrivances such as screens and shutters,
      much diversity of scenic effect is produced.
      [1913 Webster]

   2. A building used for such an exhibition.
      [1913 Webster]

WordNet (r) 3.0 (2006):

diorama
    n 1: a picture (or series of pictures) representing a continuous
         scene [syn: panorama, cyclorama, diorama]

Moby Thesaurus II by Grady Ward, 1.0:

43 Moby Thesaurus words for "diorama":
   airscape, cityscape, cloudscape, cosmorama, cyclorama, display,
   exhibit, exhibition, exposition, exterior, farmscape, georama,
   interior, landscape, light show, myriorama, pageant, pageantry,
   panorama, parade, pastoral, phantasmagoria, pomp, presentation,
   psychedelic show, representation, riverscape, scape, scene,
   seapiece, seascape, shifting scene, show, sight, skyscape,
   snowscape, spectacle, stage show, tableau, tableau vivant,
   townscape, view, waterscape