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impedance

American  
[im-peed-ns] / ɪmˈpid ns /

noun

  1. Electricity. the total opposition to alternating current by an electric circuit, equal to the square root of the sum of the squares of the resistance and reactance of the circuit and usually expressed in ohms. Z

  2. Also called mechanical impedance.  Physics. the ratio of the force on a system undergoing simple harmonic motion to the velocity of the particles in the system.

  3. something that impedes; an obstacle or hindrance.

impedance British  
/ ɪmˈpiːdəns /

noun

  1.  Z.  a measure of the opposition to the flow of an alternating current equal to the square root of the sum of the squares of the resistance and the reactance, expressed in ohms

  2. a component that offers impedance

  3. Also called: acoustic impedance.   Za.  the ratio of the sound pressure in a medium to the rate of alternating flow of the medium through a specified surface due to the sound wave

  4. Also called: mechanical impedance.   Zm.  the ratio of the mechanical force, acting in the direction of motion, to the velocity of the resulting vibration

"Collins English Dictionary — Complete & Unabridged" 2012 Digital Edition © William Collins Sons & Co. Ltd. 1979, 1986 © HarperCollins Publishers 1998, 2000, 2003, 2005, 2006, 2007, 2009, 2012
impedance Scientific  
/ ĭm-pēd′ns /

  1. A measure of the opposition to the flow of alternating current through a circuit. Impedance is measured in ohms. The resistance of a circuit to direct current (also measured in ohms) is generally not the same as its impedance, due to the effects of capacitance and induction in and among the components of the circuit.

  2. See also impedance matching

impedance Cultural  

  1. A measure of the apparent resistance posed by an electrical circuit to an alternating current (AC).

Discover More

The term impedance is most often encountered in dealing with antennas and speakers in television, stereo, and radio systems.

Other Word Forms

  • self-impedance noun

Etymology

Origin of impedance

1886; impede + -ance; term introduced by O. Heaviside

Example Sentences

Examples are provided to illustrate real-world usage of words in context. Any opinions expressed do not reflect the views of Dictionary.com.

Pulse wave velocity was measured by impedance cardiography, while carotid intima-media thickness and carotid artery distensibility were measured by carotid ultrasonography.

From Science Daily • Jun. 5, 2024

The graphene microelectrodes exhibit low impedance and high charge injection, essential attributes for flexible and efficient neural interfaces.

From Science Daily • Jan. 13, 2024

To make that diagnosis, gastroenterologists can do a test called a pH impedance study.

From Washington Post • Feb. 27, 2023

It works in a way similar to existing consumer smart scales, sending an electrical signal through your body and measuring the impedance.

From The Verge • Aug. 18, 2021

Because the receiver would offer a large impedance to the high-frequency current, that is, seriously impede and so reduce the high-frequency current, we connect a condenser around the receiver.

From Letters of a Radio-Engineer to His Son by Mills, John

Definitions and idiom definitions from Dictionary.com Unabridged, based on the Random House Unabridged Dictionary, © Random House, Inc. 2023

Idioms from The American Heritage® Idioms Dictionary copyright © 2002, 2001, 1995 by Houghton Mifflin Harcourt Publishing Company. Published by Houghton Mifflin Harcourt Publishing Company.