1) Brake of a sort 2) Chock 3) Chock of wood 4) Mine roof prop 5) Mine support 6) Prop in a mine 7) Roof prop in a coal mine 8) Timber prop 9) Wagon prop 10) Wedge 11) Wedge placed beneath a wheel 12) Wedge placed under a wheel 13) Wedge stuck under a wheel 14) Wheel chock 1) Pitprop 2) Prop 
short pit-prop (L 238)
bar inserted to stop a wheel
• (v. t.) To prop or sustain with a sprag. • (a.) See Sprack, a. • (n.) A billet of wood; a piece of timber used as a prop. • (v. t.) To check the motion of, as a carriage on a steep grade, by putting a sprag between the spokes of the wheel. • (n.) A young salmon.
slang term for a nail. 
short pit-prop (L 238)
Sprag adjective See Sprack , adjective Shak. Sprag noun [ Confer Icelandic spraka a small flounder.] (Zoology) A young salmon. [ Prov. Eng.] Sprag transitive verb [ imperfect & past participle Spragged ; present participle & verbal noun Spragging .] 1. To check the motion of, as a carriage on a steep grade, by putting a sprag between the spokes of the wheel. R. S. P...
Sprag is Australian slang for confront or accost aggressively.
[n] - a chock or bar wedged under a wheel or between the spokes to prevent a vehicle from rolling down an incline
A short length of timber tapered at each end used to slow down or stop drams by placing through the wheel spokes.
Used usually on an arête. The fingers grab a hold on one side of the arête while the thumb grabs a hold on the other side.
noun a chock or bar wedged under a wheel or between the spokes to prevent a vehicle from rolling down an incline