- a kind of mill wheel turned by the weight of persons treading steps arranged around its circumference: formerly used as an instrument of prison discipline
- a mill driven by an animal treading a sloping, endless belt
- any monotonous round of duties, work, etc. in which one seems to make no progress
- a stationary exercise machine, typically with speed controls, handles, etc., consisting of a short, wide conveyor belt upon which a person walks or runs
- A wheel with steps on which a person treads, used to power machinery.
- An exercise device consisting of a continuous moving belt on which a person or animal can walk or run while remaining in one place.
- A monotonous routine or set of tasks.
- A piece of indoor sporting equipment used to allow for the motions of running or walking while staying in one place.
- 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.
- A mill worked by horses, dogs, etc., treading an endless belt.