A permeable dimension is [...]
- stage performances: The melody of one stage transforms the atmosphere of another as it transcends time and space to meld with the performance of the other universe.
- haunted houses: A haunted house is still inhabited in another universe. Merely the shadows of actions and words come across. You are their ghost story -- they are yours.
- polygons come to mind.
- dimensions 1 through 4 (relevant or no?)