sprocket

noun

1. A toothed wheel that enmeshes with a chain or other perforated band.
2. (usually in the plural) The tooth of such a wheel.
3. A flared extension at the base of a sloped roof.
4. A placeholder name for an unnamed, unspecified, or hypothetical manufactured good or product.“Suppose we have a widget factory that produces 100 widgets per year, and a sprocket factory that produces 200 sprockets per year.”