/tred"mil'/ , n.
1. an apparatus for producing rotary motion by the weight of people or animals, treading on a succession of moving steps or a belt that forms a kind of continuous path, as around the periphery of a pair of horizontal cylinders.
2. an exercise machine that allows the user to walk or run in place, usually on a continuous moving belt.
3. any monotonous, wearisome routine in which there is little or no satisfactory progress.
[ 1815-25; TREAD + MILL 1 ]