power

power in physics, time rate of doing work or of producing or expending energy . The unit of power based on the English units of measurement is the horsepower , devised for describing mechanical power by James Watt, who estimated that a horse can do 550 ft-lb of work per sec; a foot-pound is the work done when a weight (force) of 1 lb is moved through a distance of 1 ft. The unit of power in the metric system is the watt , named in honor of James Watt and equal to 1 joule per sec; the watt is used for measuring electric power in most countries, even those still using English units for other quantities. In common usage, the terms power and energy have become synonymous; for example, electrical energy is usually referred to as electric power (see power, electric ). See also energy, sources of .

power power behind the throne a person who exerts authority or influence without having formal status.
power corrupts proverbial saying, late 19th century; now commonly used in allusion to Lord Acton (1834–1902) ‘Power tends to corrupt and absolute power corrupts absolutely.’
power of attorney a document, or clause in a document, giving a person the authority to act for another person in specified or all legal or financial matters.

See also balance of power, knowledge is power, powers.

power In physics, rate of doing work or of producing or consuming energy. It is a measure of the output of an engine or other power source. The Scottish engineer James Watt was the first to measure power; he used the unit called horsepower. The modern unit of power is the watt, named after him.