doorstop

noun

1. a device for holding a door open, as a wedge or small weight.
2. Also called slamming stile, stop. (in a doorframe) a strip or projecting surface against which the door closes.
3. a device for preventing a door from striking a wall or an object on a wall, as a small rubber-covered projection.

noun

1. a heavy object, wedge, or other device which prevents an open door from moving
2. a projecting piece of rubber, etc, fixed to the floor to stop a door from striking a wall
3. informal a very thick book