Try Our Apps

# impedance

[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. Symbol: 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.
Origin of impedance
1886
1886; impede + -ance; term introduced by O. Heaviside
Related forms
self-impedance, noun
Dictionary.com Unabridged
Based on the Random House Dictionary, © Random House, Inc. 2018.
Cite This Source
Examples from the Web for impedance
Historical Examples
• impedance, however, does not equal the sum of resistance and reactance.

Willis Eugene Tower
• What is the impedance if the voltage of the line is 115 volts?

Willis Eugene Tower
• The impedance of its secondary will be a quarter of this or 3,000 ohms.

John Mills
• The impedance of the coil I is changed by moving its adjustable core.

Kempster Miller
• impedance depends chiefly upon the frequency of alternation.

John F. Woodhull
• An important factor in the design of impedance coils is the grade of iron used in the magnetic circuit.

Kempster Miller
• The usual diagrammatic symbol for an impedance coil is shown in Fig. 106.

Kempster Miller
• The symbol of Fig. 104 is a good one for the toroidal type of impedance coil.

Kempster Miller
• These four impedance coils are wound on separate cores and do not have any inductive relation whatsoever with each other.

Kempster Miller
• In order to further increase the impedance, the cores are made long and heavy.

Kempster Miller
British Dictionary definitions for impedance

## impedance

/ɪmˈpiːdəns/
noun
1.
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 Z
2.
a component that offers impedance
3.
Also called acoustic impedance. 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 Za
4.
Also called mechanical impedance. the ratio of the mechanical force, acting in the direction of motion, to the velocity of the resulting vibration Zm
Collins English Dictionary - Complete & Unabridged 2012 Digital Edition
Publishers 1998, 2000, 2003, 2005, 2006, 2007, 2009, 2012
Cite This Source
Word Origin and History for impedance
n.

1886, from impede + -ance.

Online Etymology Dictionary, © 2010 Douglas Harper
Cite This Source
impedance in Science
 impedance   (ĭm-pēd'ns)    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. See also impedance matching.
The American Heritage® Science Dictionary
Cite This Source
impedance in Culture
impedance [(im-peed-ns)]

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

Note: The term impedance is most often encountered in dealing with antennas and speakers in television, stereo, and radio systems.
The New Dictionary of Cultural Literacy, Third Edition
Cite This Source

### Difficulty index for impedance

Many English speakers likely know this word

### Word Value for impedance

16
20
Scrabble Words With Friends