Look up impedance in Wiktionary, the free dictionary.
Impedance is the complex-valued generalization of resistance. It may refer to:
Acoustic impedance, a constant related to the propagation of sound waves in an acoustic medium
Electrical impedance, the ratio of the voltage phasor to the electric current phasor, a measure of the opposition to time-varying electric current in an electric circuit
High impedance, when only a small amount of current is allowed through