impedance

From impede +‎ -ance. In sense 2 and sense 3 it was coined by English mathematician and physicist Oliver Heaviside in 1886.

• (Received Pronunciation) IPA^(key): [ɪmˈpiːdn̩s]

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• (General American, Canada) IPA^(key): [ɪmˈpidn̩s]

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• (General Australian) IPA^(key): [ɪmˈpiːdn̩s]

impedance (countable and uncountable, plural impedances)

1. The act of impeding; that which impedes; a hindrance.
   • 2012, R. Crafton Gibbs, Spirit Growth: Logos 2, Vol. 2, of Writing God's Book of Life, page 31:

     Faithful yielding is therefore a display of love before God by preparing to respond to his Call to Arms, even though He may not send us into the front lines of battle if some disability or impedance of Satan prevents us from action […]

3. (physics) A measure of the opposition to the flow of an alternating current in a circuit; the aggregation of its resistance, and inductive and capacitive reactances; the ratio of voltage to current treated as complex quantities.
5. (physics) A quantity analogous to electrical impedance in some other energy domain
   1. (physics, usually with “mechanical”) a measure of opposition to motion of something subjected to a force; the ratio of force to velocity treated as complex quantities.
   2. (physics, usually with “acoustic” or “sound”) the ratio of sound pressure to volume flow rate treated as complex quantities.

in technical works, "impedance" is universally given the symbol Z, which is often used as a synonym for the word even in running text.

• impediment