horsepower
Americannoun
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an fps unit of power, equal to 550 foot-pounds per second (equivalent to 745.7 watts)
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a US standard unit of power, equal to 746 watts
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The horsepower is used to measure the power of engines.
This term was coined by James Watt, who invented a new type of steam engine in the eighteenth century. Watt found that the horse could do a certain amount of work per second; when he sold his steam engines, this measurement allowed him to estimate the worth of an engine in terms of the number of horses it would replace. Therefore, a six-horsepower engine was capable of replacing six horses.
Etymology
Origin of horsepower
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Example Sentences
Examples are provided to illustrate real-world usage of words in context. Any opinions expressed do not reflect the views of Dictionary.com.
AI horsepower is too expensive and precious to spin its wheels on meaningless or poorly devised tasks.
From The Wall Street Journal • Mar. 29, 2026
The Elettrica boasts 1,000 horsepower and a range of at least 329 miles, but its success hinges on appealing to traditional Ferrari enthusiasts.
From Barron's • Oct. 9, 2025
The driver had also told police his Evo sports car had 330 brake horsepower but Tregonning told the Accelerate YouTube channel that he had souped it up to almost 900 brake horsepower.
From BBC • Oct. 8, 2025
The Prius Plug-in has 220 horsepower and can accelerate from zero to 60 mph in less than 7 seconds.
From Los Angeles Times • Aug. 13, 2025
It wasn’t easy, but with the strength of three horsepower, we managed to shift the wreckage so it was no longer threatening to collapse on the baby cow serpent.
From "The Titan's Curse" by Rick Riordan
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Definitions and idiom definitions from Dictionary.com Unabridged, based on the Random House Unabridged Dictionary, © Random House, Inc. 2023
Idioms from The American Heritage® Idioms Dictionary copyright © 2002, 2001, 1995 by Houghton Mifflin Harcourt Publishing Company. Published by Houghton Mifflin Harcourt Publishing Company.