Horse power is a term used to describe the amount of energy or strength that a horse can generate. It is commonly used to measure the power of an engine, such as in a car or tractor. The term 'horse power' is derived from the fact that historically, horses were used to provide the power for many machines and vehicles. The crossword solution for the term 'horse power' is 'HAY', which is the most common type of food given to horses. HAY is a type of grass that is cut and dried for use as animal feed.