Definitions
1.nounAn electric current in which the direction of flow of the electrons reverses periodically, such as sawtooth, sinusoidal or square wave current.
2.nounAn electric current in which the direction of flow of the electrons reverses periodically by a sinusoidal law, hence having an average of zero, with positive and negative values (with a frequency of 50 Hz in Europe, 60 Hz in the US, 400 Hz for airport lighting, and some others); especially such a current produced by a rotating generator or alternator.