[ ree-ak-tuh ns ]
/ riˈæk təns /


Electricity. the opposition of inductance and capacitance to alternating current, expressed in ohms: equal to the product of the sine of the angular phase difference between current and voltage and the ratio of the effective voltage to the effective current. Symbol: XCompare capacitive reactance, inductive reactance.
Acoustics. acoustic reactance.

Origin of reactance

First recorded in 1890–95; react + -ance Unabridged Based on the Random House Unabridged Dictionary, © Random House, Inc. 2020

Example sentences from the Web for reactance

British Dictionary definitions for reactance

/ (rɪˈæktəns) /


the opposition to the flow of alternating current by the capacitance or inductance of an electrical circuit; the imaginary part of the impedance Z, Z = R + i X, where R is the resistance, i = √–1, and X is the reactance. It is expressed in ohmsCompare resistance (def. 3)
the opposition to the flow of an acoustic or mechanical vibration, usually due to inertia or stiffness. It is the magnitude of the imaginary part of the acoustic or mechanical impedance
Collins English Dictionary - Complete & Unabridged 2012 Digital Edition © William Collins Sons & Co. Ltd. 1979, 1986 © HarperCollins Publishers 1998, 2000, 2003, 2005, 2006, 2007, 2009, 2012