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• ohm
  ohm

  noun

  the standard unit of electrical resistance in the International System of Units (SI), formally defined to be the electrical resistance between two points of a conductor when a constant potential difference applied between these points produces in this conductor a current of one ampere. The resistance in ohms is numerically equal to the magnitude of the potential difference. Ω
• Ohm
  Ohm

  noun

  Georg Simon, 1787–1854, German physicist.

ohm

¹ American  

[ohm] / oʊm /

noun

• ohms
  plural

1. the standard unit of electrical resistance in the International System of Units (SI), formally defined to be the electrical resistance between two points of a conductor when a constant potential difference applied between these points produces in this conductor a current of one ampere. The resistance in ohms is numerically equal to the magnitude of the potential difference. Ω

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Ohm ² American  

[ohm] / oʊm /

noun

1. Georg Simon, 1787–1854, German physicist.

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ohm ¹ British  

/ əʊm /

noun

1. Ω. the derived SI unit of electrical resistance; the resistance between two points on a conductor when a constant potential difference of 1 volt between them produces a current of 1 ampere

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Ohm ² British  

/ əʊm /

noun

1. Georg Simon (ˈɡeːɔrk ˈziːmɔn). 1787–1854, German physicist, who formulated the law named after him

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ohm ¹ Scientific  

/ ōm /

1. The SI derived unit used to measure the electrical resistance of a material or an electrical device. One ohm is equal to the resistance of a conductor through which a current of one ampere flows when a potential difference of one volt is applied to it.

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Ohm ² Scientific  

1. German physicist who discovered the relationship between voltage, current, and resistance in an electrical circuit, now known as Ohm's law. The ohm unit of electrical resistance is named for him.

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ohm Cultural  

1. The unit of electrical resistance, named after the nineteenth-century German physicist Georg Ohm.

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Other Word Forms

Derived Forms

• ohmic
  adjective

Inflected Forms

Nouns

• ohms
  plural

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Etymology

Origin of ohm

First recorded in 1861; named after G. S. Ohm

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Explanation

An ohm is a unit of electricity — or more specifically, a unit of electrical resistance. The resistance of good electrical conductors, like copper, is measured in ohms. When it comes to electricity, there are many ways to measure it, including amps of current and volts of voltage. Ohms specifically measure the amount of resistance in an electrical current, an idea that's easiest to understand in terms of plumbing. Picture water flowing through a pipe; the water pressure is the voltage, the rate at which it flows is the current, and the size of the pipe is the resistance. Ohm is named for Georg S. Ohm, the physicist who discovered the relationship between current, voltage, and resistance.

Example Sentences

See Examples For:

ohm Ohm ohms

Because USB cables are terrible – just think about the number of bell wire USB cables with 10k ohm resistance.

From The Verge ● Mar. 8, 2022

Sometimes I just let the water pummel the top of my head and listen to the ohm of the fan’s whir, losing myself in the hug of its hum.

From Washington Post ● Oct. 27, 2021

"For illustration, here are some shorties which we'd call real $7 words, and wouldn't use here at this time without explanation: adit, erg, ergo, ohm, gloze, cozen, griff, modal, mure, snash, viable."

From Time Magazine Archive

They had discovered the X ray, the cathode ray, the electron, and radioactivity, invented the ohm, the watt, the Kelvin, the joule, the amp, and the little erg.

From "A Short History of Nearly Everything" by Bill Bryson

An ohm is equal to the resistance offered to an unvarying electric current by a column of mercury at 32° Fahr.,

From Hawkins Electrical Guide, Number One Questions, Answers, & Illustrations, A Progressive Course of Study for Engineers, Electricians, Students and Those Desiring to acquire a Working Knowledge of Electricity and its Applications by Nehemiah Hawkins

As Paul Ohm, a law professor at Georgetown University, observed in testimony to the U.S.

From Slate ● Oct. 25, 2026

“We design our products and services to protect people’s privacy because only DNA is harder to anonymize than human movements,” the company’s website says, quoting Georgetown law and privacy expert Paul Ohm.

From The Wall Street Journal ● Jul. 21, 2026

But Ohm is such a misanthrope that he’d never go to a cheery beach resort.

From Los Angeles Times ● Apr. 30, 2026

Candice Ohm, whose sixth-grade son attends one of the schools told Fox6 Milwaukee on Thursday she saw reports of a man with a gun near the courthouse on Facebook.

From Seattle Times ● Nov. 19, 2021

One of the greatest steps in the development of electrical science was taken when Dr Ohm put forward the law which he had discovered whereby pressure, current and resistance are related.

From Marvels of Scientific Invention An Interesting Account in Non-technical Language of the Invention of Guns, Torpedoes, Submarine Mines, Up-to-date Smelting, Freezing, Colour Photography, and many other recent Discoveries of Science by Thomas W. Corbin

The units of impedance are ohms, and its effect on the circuit is as you might expect: the greater the impedance, the smaller the current.

From Textbooks ● Aug. 12, 2015

The absolute value of the difference between the actual and nominal resistance should not exceed the stated variability, so, with the resistance in ohms,

From Textbooks ● Feb. 13, 2015

Unfortunately, when you buy a resistor, you can’t get one that is exactly 1000 ohms; rather, it is guaranteed to be only within 10 percent of that value.

From Salon ● Feb. 16, 2013

Electricity is sold in kilowatt-hours but electricity terminology spans other units like volts, amperes, and ohms.

From Slate ● Oct. 14, 2011

For 3 ohms it takes three times as much to give one ampere.

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

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