Switchblade

Part of speech: noun

Pronunciation: /ˈswɪt͡ʃˌbleɪd/

Definitions

1. A type of knife featuring a retractable blade that deploys automatically with the push of a button
2. A compact weapon designed with a blade that opens instantly from its handle through a mechanical action
3. A knife characterized by a blade that springs open from the handle when a mechanism is activated

Etymology: The switchblade is a plain compound: "switch" (a quick mechanical action, from the sense of a flexible rod or lash) plus "blade." The name describes the mechanism rather than the knife's shape or use. A spring-loaded catch releases the blade so it snaps out at the press of a button or the flick of a lever, and the word fixes on that switching action. The idea of the sudden-opening knife is older than the name. What the compound adds is the emphasis on the snap itself, the moment the closed knife becomes a weapon in a single motion. Its plainness is the point: nobody had to coin a fancy term, because the mechanism was the most striking thing about the object.

Synonyms: automatic knife, folding knife, spring knife