What is another word for "piston"?

Roget's Thesaurus (1911) lists these synonyms for "piston": beadle, bung, cerberus, cork, cover, doorkeeper, dossil, janitor, ostiary, padding, peg, pledget, plug, porter, ram, rammer, ramrod, slide, spigot, spike, spill, stop-gap, stopcock, stopper, stopping, stopple, stuffing, tap, tompion, tourniquet, valve, vent, wadding, warder.