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[kop-er] /ˈkɒp ər/
a malleable, ductile, metallic element having a characteristic reddish-brown color: used in large quantities as an electrical conductor and in the manufacture of alloys, as brass and bronze. Symbol: Cu; atomic weight: 63.54; atomic number: 29; specific gravity: 8.92 at 20°C.
a metallic reddish brown.
a coin composed of copper, bronze, or the like, as the U.S. cent or the British penny.
any of several butterflies of the family Lycaenidae, as Lycaena hypophleas (American copper) having copper-colored wings spotted and edged with black.
a container made of copper.
a tool partly or wholly made of copper:
a soldering copper.
British. a large kettle, now usually made of iron, used for cooking or to boil laundry.
made of copper:
copper kettles.
reddish-brown; coppery:
The copper sun sank into the sea.
verb (used with object)
to cover, coat, or sheathe with copper.
Informal. hedge (def 6).
Origin of copper1
before 1000; Middle English coper, Old English coper, copor (cognate with Old Norse koparr, German Kupfer) < Late Latin cuprum, for Latin (aes) Cyprium Cyprian (metal)


[kop-er] /ˈkɒp ər/
noun, Slang.
a police officer.
1840-50, Americanism; perhaps cop1 + -er1 Unabridged
Based on the Random House Dictionary, © Random House, Inc. 2018.
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Examples from the Web for copper
Contemporary Examples
Historical Examples
  • "And copper's up two points to-day," said Percival, cheerfully.

    The Spenders Harry Leon Wilson
  • The movements in copper and Cordage Trust stocks are purely speculative.

    The Spenders Harry Leon Wilson
  • Here's copper just closed at 93, after opening strong this morning at 105.

    The Spenders Harry Leon Wilson
  • "Why, he copped the copper's kale," Aggie translated, glibly.

    Within the Law Marvin Dana
  • Since then we have greatly diminished the iron and increased the copper.

British Dictionary definitions for copper


  1. a malleable ductile reddish metallic element occurring as the free metal, copper glance, and copper pyrites: used as an electrical and thermal conductor and in such alloys as brass and bronze. Symbol: Cu; atomic no: 29; atomic wt: 63.546; valency: 1 or 2; relative density: 8.96; melting pt: 1084.87±+0.2°C; boiling pt: 2563°C related adjectives cupric cuprous related prefix cupro-
  2. (as modifier): a copper coin
  1. the reddish-brown colour of copper
  2. (as adjective): copper hair
(informal) any copper or bronze coin
(mainly Brit) a large vessel, formerly of copper, used for boiling or washing
any of various small widely distributed butterflies of the genera Lycaena, Heodes, etc, typically having reddish-brown wings: family Lycaenidae
(transitive) to coat or cover with copper
Derived Forms
coppery, adjective
Word Origin
Old English coper, from Latin Cyprium aes Cyprian metal, from Greek Kupris Cyprus


a slang word for policeman Often shortened to cop
Word Origin
C19: from cop1 (vb) + -er1
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
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Word Origin and History for copper

malleable metallic element, Old English coper, from West Germanic *kupar (cf. Middle Dutch koper, Old Norse koparr, Old High German kupfar), from Late Latin cuprum, contraction of Latin Cyprium (aes) "Cyprian (metal)," after Greek Kyprios "Cyprus" (see Cyprus).

Latin aes originally was "copper," but this was extended to its alloy with tin, bronze, and as this was far more extensively used than pure copper, the word's primary sense shifted to the alloy and a new word evolved for "copper," from the Latin form of the name of the island of Cyprus, where copper was mined. Aes passed into Germanic (which originally did not distinguish copper from its alloys) and became English ore. In Latin, aes was the common word for "cash, coin, debt, wages" in many figurative expressions. Chemical symbol Cu is from cuprum.


"policeman," 1846; agent noun from cop (v.).

Online Etymology Dictionary, © 2010 Douglas Harper
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copper in Medicine

copper cop·per (kŏp'ər)
Symbol Cu
A ductile malleable metallic element that is an excellent conductor of heat and electricity and is used for electrical wiring, water piping, and corrosion-resistant parts, either pure or in alloys such as brass and bronze. Atomic number 29; atomic weight 63.546; melting point 1,085°C; boiling point 2,562°C; specific gravity 8.96; valence 1, 2.

The American Heritage® Stedman's Medical Dictionary
Copyright © 2002, 2001, 1995 by Houghton Mifflin Company. Published by Houghton Mifflin Company.
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copper in Science
Symbol Cu
A reddish-brown, ductile, malleable metallic element that is an excellent conductor of heat and electricity. It is widely used for electrical wires, water pipes, and rust-resistant parts, either in its pure form or in alloys such as brass and bronze. Atomic number 29; atomic weight 63.546; melting point 1,083°C; boiling point 2,595°C; specific gravity 8.96; valence 1, 2. See Periodic Table. See Note at element.
Copper and Stone Age  
See Chalcolithic.
The American Heritage® Science Dictionary
Copyright © 2002. Published by Houghton Mifflin. All rights reserved.
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Slang definitions & phrases for copper

copper 1


  1. A police officer (1846+)
  2. An informer; stool pigeon (1897+ Underworld)
  3. Time taken off a prison sentence for good behavior or because one has informed on colleagues (1908+ Underworld)

copper 2


To bet against a card, roll of the dice, person, etc

[1864+ Gambling; fr the use of a special metal chip, often a copper cent, by a gambler to indicate a bet with the bank in faro]

The Dictionary of American Slang, Fourth Edition by Barbara Ann Kipfer, PhD. and Robert L. Chapman, Ph.D.
Copyright (C) 2007 by HarperCollins Publishers.
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