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  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. Symbol: Ω

Origin of ohm

First recorded in 1861; named after G. S. Ohm
Related formsohm·ic [oh-mik] /ˈoʊ mɪk/, adjective


  1. Ge·org Si·mon, [gey-awrk zee-mawn] /geɪˈɔrk ˈzi mɔn/1787–1854, German physicist.
Dictionary.com Unabridged Based on the Random House Unabridged Dictionary, © Random House, Inc. 2018

Examples from the Web for ohm

Historical Examples

  • Wheatstone by his knowledge of Ohm's law and the electro-magnet was probably able to enlighten him.

    Heroes of the Telegraph

    J. Munro

  • We must therefore have a standard for the ohm, which is the measure of resistance.

  • In applying this illustration to the voltaic cell, we make use of Ohm's law.


    Willis Eugene Tower

  • One of these methods depends upon an application of Ohm's law.


    Willis Eugene Tower

  • This furlough was perhaps the most important event in Ohm's life.

    Makers of Electricity

    Brother Potamian

British Dictionary definitions for ohm


  1. 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 ampereSymbol: Ω

Word Origin

C19: named after Georg Simon Ohm


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

Word Origin and History for ohm


unit of electrical resistance, 1867, in recognition of German physicist Georg S. Ohm (1789-1854), who determined the law of the flow of electricity. Originally proposed as ohma (1861) as a unit of voltage. Related: ohmage; ohmic; ohmeter.

Online Etymology Dictionary, © 2010 Douglas Harper

ohm in Medicine


([object Object])
n. Symbol Ω
  1. A unit of electrical resistance equal to that of a conductor in which a current of one ampere is produced by a potential of one volt across its terminals.
The American Heritage® Stedman's Medical Dictionary Copyright © 2002, 2001, 1995 by Houghton Mifflin Company. Published by Houghton Mifflin Company.

ohm in Science


  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.


  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.
The American Heritage® Science Dictionary Copyright © 2011. Published by Houghton Mifflin Harcourt Publishing Company. All rights reserved.

ohm in Culture



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

The New Dictionary of Cultural Literacy, Third Edition Copyright © 2005 by Houghton Mifflin Harcourt Publishing Company. Published by Houghton Mifflin Harcourt Publishing Company. All rights reserved.
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