Horsepower, HP, or H.P. (noun) a 746-watt power unit. The term comes from the British horsepower, which is a unit of mechanical power equal to 0.746 newtons meters squared per second. One horsepower is defined as the force needed to lift 1 pound over a distance of 1 foot high by an ordinary man working at a rate of 100 strokes per minute. The symbol for horsepower is hp. HP has been used as an acronym for many things over the years including: His Permission, Harvard Ph. D., How Philip Reaches Mars, High Performance, Highway Patrol, and more. It was also used by Thomas Edison as an abbreviation for his phonograph company before he changed the name to General Electric. Finally, it is used by IBM as an acronym for their various brands such as "Human Processing" and "Hebrew Programming Language." HP has no real meaning behind it other than being a placeholder in case someone needs to know what the manufacturer of your computer's power supply is called. However, some people may try to connect your household purchase with important dates or people in your life.