- treadmill - an exercise device consisting of an endless belt on which a person can walk or jog without changing place
--1 is a kind of exercise device
- treadmill, treadwheel, tread-wheel - a mill that is powered by men or animals walking on a circular belt or climbing steps
--2 is a kind of mill, grinder
- treadmill, salt mine - a job involving drudgery and confinement
--3 is a kind of occupation, business, job, line of work, line
- treadmill, treadwheel, tread-wheel - a mill that is powered by men or animals walking on a circular belt or climbing steps