What does "cotter" mean?

Cotter: A piece of wood or metal, commonly wedge-shaped, used for fastening together parts of a machine or structure. It is driven into an opening through one or all of the parts. Note: [See Illust.] In the United States a cotter is commonly called a key.

Additional senses

  1. 2.A toggle.
  2. 3.To fasten with a cotter.

Sources