lever

A lever ( or ) is a machine consisting of a beam or rigid rod pivoted at a fixed hinge, or . A lever is a rigid body capable of rotating on a point on itself. It is one of the six simple machines identified by Renaissance scientists. The word entered English about 1300 from Old French, in which the word was levier. This sprang from the stem of the verb lever, meaning "to raise". The verb, in turn, goes back to the Latin levare, itself from the adjective levis, meaning "light" (as in "not heavy"). The word's ultimate origin is the Proto-Indo-European (PIE) stem legwh-, meaning "light", "easy" or "nimble", among other things. The PIE stem also gave rise to the English word "light". A lever amplifies an input force to provide a greater output force, which is said to provide leverage. The ratio of the output force to the input force is the mechanical advantage of the lever.