Etymology
Advertisement

treadmill (n.)

invented (and named) 1822; originally an instrument of prison discipline; from tread (v.) + mill (n.1). Treadwheel as a similar method of driving machinery is from 1570s.

As a corrective punishment, the discipline of the stepping mill has had a most salutary effect upon the prisoners, and is not likely to be easily forgotten, while it is an occupation which by no means interferes with, nor is calculated to lessen the value of, those branches of prison regulation which provide for the moral and religious improvement of the criminal. ["Description of the Tread Mill Invented by Mr. William Cubitt of Ipswich for the Employment of Prisoners," London, 1822]

By later generations regarded as a path to physical fitness.

Advertisement
Advertisement
Definitions of treadmill

treadmill (n.)
an exercise device consisting of an endless belt on which a person can walk or jog without changing place;
treadmill (n.)
a mill that is powered by men or animals walking on a circular belt or climbing steps;
Synonyms: treadwheel / tread-wheel
treadmill (n.)
a job involving drudgery and confinement;
Synonyms: salt mine
From wordnet.princeton.edu