sprag

A piece of wood or metal wedged beneath a wheel or between spokes to keep a vehicle from rolling.

A pointed stake lowered at an angle into the ground from a vehicle to prevent movement.

A prop to support a mine roof.

To prop by a sprag; also, to stop, as a carriage on a steep grade, by putting a sprag in the spokes of the wheel.

A billet of wood.

Specifically In coal-mining: A short billet of wood used instead of a brake to lock the wheels of a car.

A short wooden prop used to support the coal during the operation of holing or undercutting; a punch-prop.

A young salmon of the first year; a smolt.

A half-grown cod.