An Etymological Dictionary of Astronomy and Astrophysics

A unit of power in the SI or MKS system of units, symbol W, equivalent to one joule per second.
1 W = 1 J s^-1 = 1 kg m² s^-3 = 1 N m s^-1 = 10⁷ erg s^-1.
Electricity: The current in amperes multiplied by the electrical potential in volts.

See also: In honor of James Watt (1736-1819) the eminent Scottish inventor and mechanical engineer.