[ree-ak-tuh
ns] 
| 1. | 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: X Compare capacitive reactance, inductive reactance. |
| 2. | Acoustics. acoustic reactance. |
| acoustic impedance caused by the inertia and elasticity of the transmitting medium. |
| re·ac·tance (rē-āk'təns) n. Symbol X Electricity Opposition to the flow of alternating current caused by the inductance and capacitance in a circuit rather than by resistance. |