An electric current that reverses direction sinusoidally WordNet 3.0 & Open English WordNet

Alternating current is an electric current which periodically reverses direction and changes its magnitude continuously with time, in contrast to direct current, which flows only in one direction. Wikipedia

A flow of electric charge that periodically reverses direction Wikipedia Disambiguation

Electric voltage which periodically reverses direction; form in which electric power is delivered to businesses and residences; form of electrical energy that consumers typically use when they plug electric appliances into a wall socket Wikidata

A current that flows alternately in one direction and then in the reverwse direction. OmegaWiki

An 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. Wiktionary