1. (noun) a mill that is powered by men or animals walking on a circular belt or climbing steps

• tread-wheel
• treadwheel

2. (noun) a job involving drudgery and confinement

• salt mine

1. (noun) an exercise device consisting of an endless belt on which a person can walk or jog without changing place

• exercise device

2. (noun) a mill that is powered by men or animals walking on a circular belt or climbing steps

• grinder
• mill
• milling machinery

3. (noun) a job involving drudgery and confinement

• business
• job
• line
• line of work
• occupation