Undescribed object
From IFWiki
Something that is mentioned in the game text but is not actually implemented. This can result in a mimesis-breaking response from the parser when the player tries to interact with it, such as "You can see no such thing".
One way to correct this problem in many authoring systems is to make the object into scenery, which will generate a more helpful response, such as "The <object> is not important".
Links
- Undescribed Objects in the IF Gems review quotes collection (also available from the IF Archive).