A mill worked by persons treading upon steps on the periphery of a wide wheel having a horizontal axis. It is used principally as a means of prison discipline. Also, a mill worked by horses, dogs, etc., treading an endless belt.
- A mechanism rotated by people treading on the moving steps of a wheel.
- A similar device operated by an animal treading a continuous sloping belt.
- An exercise device consisting of a continuous moving belt on which a person can walk or jog while remaining in one place.
- A monotonous task or set of tasks seeming to have no end.