• (n.) A framework of timber covered with boards to support rubbish; also, a framework of boards to protect miners from falling stones.
Stull noun [ CF. Stum .] A framework of timber covered with boards to support rubbish; also, a framework of boards to protect miners from falling stones. [ Prov. Eng.] 
Platforms of timbers between levels for strengthening the mine by supporting the walls, and for storing ore and depositing wall rock and waste material.
A beam.
a timber prop. · a timber wedged in place between two walls of a stope as part of a protective covering or platform.