(sometimes figurative) To support or shore up something.
Try using a phone book to prop up the table where the foot is missing.
To play rugby in the prop position
(usually with "up" - see prop up) To position the feet of (a person) while sitting, lying down, or reclining so that the knees are elevated at a higher level.
To manually start the engine of a propeller-driven aircraft with no electric starter by pulling vigorously on one of the propeller blades using the hands, so that the propeller can catch ignition.
The act by which something is propped.