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horsepower

American  
[hawrs-pou-er] / ˈhɔrsˌpaʊ ər /

noun

  1. a foot-pound-second unit of power, pow, power, equivalent to 550 foot-pounds per second, or 745.7 watts.

  2. Informal. the capacity to achieve or produce; strength or talent.

    The university's history faculty is noted for its intellectual horsepower.
horsepower British  
/ ˈhɔːsˌpaʊə /

noun

  1. an fps unit of power, equal to 550 foot-pounds per second (equivalent to 745.7 watts)

  2. a US standard unit of power, equal to 746 watts

"Collins English Dictionary — Complete & Unabridged" 2012 Digital Edition © William Collins Sons & Co. Ltd. 1979, 1986 © HarperCollins Publishers 1998, 2000, 2003, 2005, 2006, 2007, 2009, 2012
horsepower Scientific  
/ hôrs′pou′ər /

  1. A unit that is used to measure the power of engines and motors. One unit of horsepower is equal to the power needed to lift 550 pounds one foot in one second. This unit has been widely replaced by the watt in scientific usage; one horsepower is equal to 745.7 watts.

horsepower Cultural  

  1. A unit of power equal to about 746 watts.

Discover More

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

First recorded in 1800–10; horse + power

Compare meaning

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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.

One theory on the F1 paddock was that Mercedes had discovered a hack with regard to engine compression ratios, a technical spec that ultimately affects engine horsepower.

From The Wall Street Journal • Mar. 8, 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

Afterward Laura and Mary asked questions, and Pa told them that the big machine was called the separator, and the rod was called the tumbling rod, and the little machine was called the horsepower.

From "Little House in the Big Woods" by Laura Ingalls Wilder

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.