from
The Collaborative International Dictionary of English v.0.48
Reactance \Re*act"ance\ (r[-e]*[a^]k"tans), n. [React + -ance.]
(Elec.)
The influence of a coil of wire upon an alternating current
passing through it, tending to choke or diminish the current,
or the similar influence of a condenser; inductive
resistance. Reactance is measured in ohms. The reactance of a
circuit is equal to the component of the impressed
electro-motive force at right angles to the current divided
by the current, that is, the component of the impedance due
to the self-inductance or capacity of the circuit.
[Webster 1913 Suppl.]