volt-amperes reactive (VAR): In alternating-current power transmission and distribution, the product of the rms voltage and current, i.e., the apparent power, multiplied by the sine of the phase angle between the voltage and the current.

The term VAR was introduced in 1930 by the IEC in Stockholm. The symbol N is usually used for the quantity measured in VARs.

Note 1: Vars represents the power not consumed by a reactive load, i.e., when there is a phase difference between the applied voltage and the current.

Note 2: Only effective power, i.e., the actual power delivered to or consumed by the load, is expressed in watts. Volt-amperes reactive is properly expressed only in volt-amperes, never watts.

Note 3: To maximize transmission efficiency, vars must be minimized by balancing capacitive and inductive loads, or by the addition of an appropriate capacitive or inductive reactance to the load.

Source: from Federal Standard 1037C