Sprag

Part of speech: noun

Definitions

1. A wedge or bar placed under a wheel to prevent it rolling ; any prop or object used to hold something in place or support a load
2. A block or metal bar inserted beneath a wheel as a brake or safety stop ; a strut or brace used to prevent movement or collapse
3. A chock positioned under a wheel to lock it in position ; any structural support or prop used to stabilize or hold up an object

Etymology: "Sprag" is a nautical and mining term, and its story is tangled up with the word "spray" in its older sense of a branch or twig. A sprag was originally a short stick or pole, and the connection to "spray" points back to that bundle of twigs image. In practical use, a sprag is a wedge or bar jammed into machinery or a wheel to stop it turning, which is how the sense of a brake or check developed from the simple stick. The same idea of a piece of wood thrust in to hold something in place carries over into the term's later technical uses.

Synonyms: wedge, chock, prop