noun A piece of indoor sporting equipment used to allow for the motions of running or walking while staying in one place.
noun A mill worked by persons treading upon steps on the periphery of a wide wheel having a horizontal axis. It was used principally as a means of prison discipline.
noun A mill worked by horses, dogs, etc., treading an endless belt.
noun A process or situation in which continued effort leads to or is required for remaining at a particular state or level without moving ahead.
verb To exercise on a treadmill.
verb To keep busy, for example, with work or with other tasks, without being able to get ahead or make progress towards long-term goals.