a model representing a scene with three-dimensional figures, either in miniature or as a large-scale museum exhibit.
chiefly historical a scenic painting, viewed through a peephole, in which changes in colour and direction of illumination simulate changes in the weather, time of day, etc..
a miniature film set used for special effects or animation.
Origin:
early 19th century: coined in French from dia- 'through', on the pattern of panorama
diorama in other Oxford dictionaries
Definition of diorama in the US English dictionary