From IFWiki

The term scenery has two distinct uses, which often overlap but are not mutually necessary:

  • an object which does not appear in the object-listing of a room; usually it will be immobile and cannot be taken by the player. Either it will be mentioned in the description of the room, or will become apparent on the closer perusal of other mentioned objects. It may be of considerable use to the player, however. This sense of the word is more commonly used in the context of an object's code properties, rather than its appearance in the game world.
  • an object with no in-game use, unmovable by the player, which only appears in order to add to the realism of the environment. It may have a few responses for obvious actions taken on it by the player, but these are only for flavour and don't change anything important, or give any useful information.