What does the unit "hp" means? I admit that my physics sucks because it has been a long time since I heard the word "physics" but putting that aside, what does the unit "hp" represent/means? I don't remember learning that unit in school. Eg. An engine develops 85hp I'm guessing it's a Power unit and if it is, would it be like 85 hp = 8500 watts/J? or would it just be 85hp?