TREADMILL

treadmill, salt mine

(noun) a job involving drudgery and confinement

treadmill, treadwheel, tread-wheel

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

treadmill

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

Source: WordNet® 3.1

Etymology

Noun

treadmill (plural treadmills)

A piece of indoor sporting equipment used to allow for the motions of running or walking while staying in one place.

(historical) A mill worked by persons treading upon steps on the periphery of a wide wheel having a horizontal axis. It is used principally as a means of prison discipline.

A mill worked by horses, dogs, etc, treading an endless belt.

Source: Wiktionary

Tread"mill`, n.

Definition: A mill worked by persons treading upon steps on the periphery of a wide wheel having a horizontal axis. It is used principally as a means of prison discipline. Also, a mill worked by horses, dogs, etc., treading an endless belt.

Source: Webster’s Unabridged Dictionary 1913 Edition