treadmill

American  

[tred-mil] / ˈtrɛdˌmɪl /

noun

1. an apparatus for producing rotary motion by the weight of people or animals, treading on a succession of moving steps or a belt that forms a kind of continuous path, as around the periphery of a pair of horizontal cylinders.

2. an exercise machine that allows the user to walk or run in place, usually on a continuous moving belt.

3. any monotonous, wearisome routine in which there is little or no satisfactory progress.

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treadmill British  

/ ˈtrɛdˌmɪl /

noun

1. Also called: treadwheel.  (formerly) an apparatus used to produce rotation, in which the weight of men or animals climbing steps on or around the periphery of a cylinder or wheel caused it to turn

2. a dreary round or routine

3. an exercise machine that consists of a continuous moving belt on which to walk or jog

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Etymology

Origin of treadmill

First recorded in 1815–25; tread + mill ¹

Explanation

A treadmill is an exercise machine for walking or running in place. If it's bitterly cold outside, you might decide to go to the gym and run on the treadmill instead of taking your usual outdoor jog. A treadmill was originally a type of human- or animal-powered machine. By walking on a wheel fitted with steps, a person (or animal) turned it, grinding grain in the process. Treadmills were also used as punishment in prisons where inmates were forced to work. Today the only treadmills you're likely to see are in a gym, but the word is commonly used in a figurative way for any relentless, boring job.

Example Sentences

The pattern holds whether scientists are testing how fast lizards run on a treadmill, measuring how sharks swim in the ocean, or tracking how quickly bacterial cells divide.

From Science Daily • Mar. 12, 2026

“Maybe what I need to do is just celebrate all I’ve done instead of getting back into this rat race, on this treadmill, and look for something totally different,” he said.

From Los Angeles Times • Mar. 6, 2026

The lawyer said these efforts enticed users to a "treadmill of continuous checking" for new content.

From Barron's • Feb. 23, 2026

You have to buy an entirely new bike, treadmill or row machine, starting at $2,695, plus a $50-a-month subscription.

From The Wall Street Journal • Jan. 4, 2026

“The ocean current is like a treadmill beneath our keel,” the captain tells me.

From "Challenger Deep" by Neal Shusterman