sprocket

noun

1. 1

   A toothed wheel that enmeshes with a chain or other perforated band.

2. 2

   (usually in the plural) The tooth of such a wheel.

3. 3

   A flared extension at the base of a sloped roof.

4. 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.”