A device formerly used for driving machinery, consisting of a large wheel with steps fitted into its inner surface. It was turned by the weight of people or animals treading the steps. An exercise machine, typically with a continuous belt, that allows one to walk or run in place. A job involving drudgery and confinement.

An exercise machine, typically with a continuous belt, that allows one to walk or run in place. An exercise device consisting of an endless belt on which a person can walk or jog without changing place. A job or situation that is tiring, boring, or unpleasant and from which it is hard to escape. Render visible, as by means of MRI.