Watt

A metric unit of power defined as one Joule per second. The Joule is a unit of energy, so power equates to the rate of energy transfer, or the rate of doing work. Named after James Watt, the developer of the practical steam engine, the watt has become a common term in audio as used to describe the power handling capabilities and/or requirements of speakers, and the power delivery capabilities of amplifiers. Milliwatts (1/1000 of a watt) are often used to describe energy usage in low power electrical circuits.