means In electrical circuits, impedance is the total opposition a circuit presents to alternating current, combining plain resistance with reactance — the frequency-dependent push-back from capacitors and inductors — and so it carries both a magnitude and a phase angle.

from From the verb 'impede,' which comes through Latin 'impedire' — literally 'to shackle the feet,' from 'in-' (in, on) plus 'pes, pedis' (foot), the same foot you'll find in 'pedal' and 'pedestrian.' So at its root it pictures something caught by the ankles, unable to move freely. The '-ance' suffix turns the act of impeding into a measurable quantity, and the word was adopted into electrical science by physicist Oliver Heaviside in the late 19th century to name this richer, AC-flavored cousin of resistance.