horse·pow·er / ˈhôrsˌpou(-ə)r/ (abbr.: hp) • n. (pl. same) a unit of power equal to 550 foot-pounds per second (745.7 watts). ∎  the power of an engine measured in terms of this: a strong 140-horsepower engine. See also brake horsepower. ∎  power; ability to perform strenuous tasks: other software improvements include more analytical horsepower.

horsepower (hp) Unit indicating the rate at which work is done, adopted by James Watt in the 18th century. He defined it as the weight, 250kg (550lb), a horse could raise 0.3m (1ft) in one second. The electrical equivalent of 1 hp is 746 watts.

horsepower an imperial unit of power equal to 550 foot-pounds per second (about 750 watts); the power of an engine measured in terms of this.