horsepower
n. uncountablen. a unit used to measure the power of an engine. It tells you how much work a car or machine can do in a certain amount of time.
n. a unit of power equal to 550 foot-pounds per second or approximately 746 watts. Often used to quantify the output of internal combustion engines or electric motors.
The new sports car has over 400 horsepower.
When choosing a tractor, the farmer looked for high horsepower to ensure it could pull heavy machinery across the muddy fields.
Engineers managed to increase the vehicle's horsepower without sacrificing fuel efficiency by implementing a more sophisticated turbocharging system and reducing the overall weight of the chassis.
From horse + power: the unit was originally defined as the amount of power that a horse could provide. Both non-metric and metric units of power were derived from effectively identical measurements of the power a draught horse could sustain over several hours, with the difference in watts solely due to different rounding errors to express that power in round numbers in the original non-SI units (ft·lbf/min and kgf⋅m/s respectively).
Usually treated as uncountable when referring to the general power of an engine, though specific figures are often cited as a number followed by the word.