horsepower is defined as work per unit of
(hÃ´rsâ²pouâ²Ér) A unit 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. (hp) A unit of work representing the power needed to raise 550 lb by 1 ft in 1 s.