• synonyms


or am·père

[am-peer, am-peer]
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noun Electricity.
  1. the basic unit of electrical current in the International System of Units(SI), equivalent to one coulomb per second, formally defined to be the constant current which if maintained in two straight parallel conductors of infinite length, of negligible circular cross section, and placed one meter apart in vacuum, would produce between these conductors a force equal to 2 × 10−7 newton per meter of length. Abbreviation: A, amp.
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Origin of ampere

First recorded in 1881; named after A. M. Ampère


[am-peer; French ahn-per]
  1. An·dré Ma·rie [ahn-drey muh-ree; French ahn-drey ma-ree] /ˈɑn dreɪ məˈri; French ɑ̃ˈdreɪ maˈri/, 1775–1836, French physicist.
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Related formsAm·per·i·an [am-peer-ee-uh n, -per-] /æmˈpɪər i ən, -ˈpɛr-/, adjective
Dictionary.com Unabridged Based on the Random House Unabridged Dictionary, © Random House, Inc. 2018

Examples from the Web for ampere

Historical Examples

  • The filament current of an audion-bulb averages about one ampere.

    The Automobile Storage Battery

    O. A. Witte

  • A 40-watt-incandescent lamp takes about 0.4 ampere of current.


    Willis Eugene Tower

  • But it is a little different when one is interested in an ampere.

  • Now I want to tell you how the physicists at the Bureau know what is an ampere.

  • A mil-ampere is a thousandth of an ampere just as a millimeter is a thousandth of a meter.

British Dictionary definitions for ampere


  1. the basic SI unit of electric current; the constant current that, when maintained in two parallel conductors of infinite length and negligible cross section placed 1 metre apart in free space, produces a force of 2 × 10 –7 newton per metre between them. 1 ampere is equivalent to 1 coulomb per second
  2. a former unit of electric current (international ampere); the current that, when passed through a solution of silver nitrate, deposits silver at the rate of 0.001118 gram per second. 1 international ampere equals 0.999835 ampere
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Abbreviation: ampSymbol: A

Word Origin

C19: named after André Marie Ampère


  1. André Marie (ɑ̃dre mari). 1775–1836, French physicist and mathematician, who made major discoveries in the fields of magnetism and electricity
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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 ampere


1881, "the current that one volt can send through one ohm," from French ampère, named for French physicist André-Marie Ampère (1775-1836). Shortened form amp is attested from 1886.

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Online Etymology Dictionary, © 2010 Douglas Harper

ampere in Medicine


  1. A unit of electric current in the meter-kilogram-second system, equal to the current that, flowing in two parallel wires one meter apart, produces a force of 2 X 10-7 newtons per meter.
  2. A unit in the International System specified as one International coulomb per second and equal to 0.999835 ampere.
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The American Heritage® Stedman's Medical Dictionary Copyright © 2002, 2001, 1995 by Houghton Mifflin Company. Published by Houghton Mifflin Company.

ampere in Science


  1. The SI unit used to measure electric current. Electric current through any given cross-section (such as a cross-section of a wire) may be measured as the amount of electrical charge moving through that cross-section in one second. One ampere is equal to a flow of one coulomb per second, or a flow of 6.28 X 1018 electrons per second.
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[ămpîr′, äm-pĕr]
  1. French mathematician and physicist who is best known for his analysis of the relationship between magnetic force and electric current. He formulated Ampère's law, which describes the strength of the magnetic field produced by the flow of energy through a conductor. The ampere unit of electric current is named for him.
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The American Heritage® Science Dictionary Copyright © 2011. Published by Houghton Mifflin Harcourt Publishing Company. All rights reserved.