impedance - technical definition

(1) The opposition to the flow of alternating current in a circuit. Represented by the letter "Z" and measured in ohms, impedance is the combination of resistance, inductance and capacitance of the circuit. See ohm.

(2) The opposition that a speaker produces to the alternating current coming from an amplifier. The lower the impedance, the more power required. Most speakers have an impedance of four to eight ohms. See ohm.