Oxford Dictionary English horsepower nounnoun BrE BrE//ˈhɔːspaʊə(r)// ; NAmE NAmE//ˈhɔːrspaʊər// [countable, uncountable] (pl. horsepower) (abbreviation h.p.) Add to my wordlistjump to other results a unit for measuring the power of an engine a powerful car with a 170 horsepower engineSee horsepower in the Oxford Advanced American DictionaryCheck pronunciation: horsepower oxfordlearnersdictionaries.com