Noun
The power which a horse exerts.
A unit of power, used in stating the power required to drive machinery, and in estimating the capabilities of animals or steam engines and other prime movers for doing work. It is the power required for the performance of work at the rate of 33,000 English units of work per minute; hence, it is the power that must be exerted in lifting 33,000 pounds at the rate of one foot per minute, or 550 pounds at the rate of one foot per second, or 55 pounds at the rate of ten feet per second, etc.
A machine worked by a horse, for driving other machinery; a horse motor.
Source: Webster's dictionaryhorse-power
Those who have come into Formula One without experiencing cars devoid of electronic aids will find it tough. To control 800 horse power relying just on arm muscles and foot sensitivity can turn out to be a dangerous exercise. Michael Schumacher
With twelve horse power at our command, we considered that we could permit the weight of the machine with operator to rise to 750 or 800 pounds, and still have as much surplus power as we had originally allowed for in the first estimate of 550 pounds. Orville Wright
When the motor was completed and tested, we found that it would develop 16 horse power for a few seconds, but that the power rapidly dropped till, at the end of a minute, it was only 12 horse power. Orville Wright