I. ˈ ̷ ̷ˌ ̷ ̷ noun
Etymology: tread (I) + mill
1.
a. : a mill worked by persons treading on steps on the periphery of a wide wheel having a horizontal axis and used formerly in prison discipline
b. : a mill worked by an animal (as a horse or dog) treading an endless belt and used also on a stock farm or ranch to exercise a bull difficult to control as well as to utilize his power for belt operations
c. : a similar device used in studies of physiological functions
2. : a wearisome routine resembling continued activity on a treadmill
II. intransitive verb
: to labor on or as if on a treadmill
III. noun
: a device having an endless belt on which an individual walks or runs in place (as for exercise)