Doorstop

noun

1. Any device or object used to halt the motion of a door, as a large or heavy object, a wedge, or some piece of hardware fixed to the floor, door or wall.
2. A large book, which by implication could be used to stop a door.
3. (in error for doorstep) A thick sandwich.
4. An interview with a politician or other public figure (apparently informal or spontaneous but often planned), as they enter or leave a building.