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[ka-feen, kaf-een, kaf-ee-in] /kæˈfin, ˈkæf in, ˈkæf i ɪn/
noun, Chemistry, Pharmacology
a white, crystalline, bitter alkaloid, C 8 H 10 N 4 O 2 , usually derived from coffee or tea: used in medicine chiefly as a nervous system stimulant.
Also, caffein.
Origin of caffeine
1820-30; < French caféine, equivalent to café coffee + -ine -ine2
Related forms
[ka-fee-nik, kaf-ee-in-ik] /kæˈfi nɪk, ˌkæf iˈɪn ɪk/ (Show IPA),
noncaffeine, noun
noncaffeinic, adjective Unabridged
Based on the Random House Dictionary, © Random House, Inc. 2015.
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Examples from the web for caffeine
  • caffeine is a substance that is found in certain plants.
  • Sometimes that requires a caffeine source or several sometimes that requires a trip to the gym.
  • It could be a close vote, but taxing caffeine has unfortunate precedents.
  • Alkaloids, which include caffeine and nicotine, are a highly diverse group of chemicals with many unusual properties.
  • For many coffee lovers, their precious beverage comes with an unwanted ingredient: caffeine.
  • Choose from molecular earrings, a caffeine molecule necklace, or a circuit board pendant.
  • Some people can't start their day without a caffeine jolt from a cup of coffee.
  • caffeine is a substance that exists naturally in certain plants.
  • caffeine could be added to keep drinkers awake during boring dinner parties.
  • So much coffee is consumed that scientists have found that caffeine permeates the local seawater.
British Dictionary definitions for caffeine


/ˈkæfiːn; ˈkæfɪˌiːn/
a white crystalline bitter alkaloid responsible for the stimulant action of tea, coffee, and cocoa: a constituent of many tonics and analgesics. Formula: C8H10N4O2 See also xanthine (sense 2)
Word Origin
C19: from German Kaffein, from Kaffeecoffee
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 caffeine

trimethyl-derivative of xanthine, 1830, from German Kaffein, coined by chemist F.F. Runge (1795-1867), apparently from German Kaffee "coffee" (see coffee) + chemical suffix -ine (2) (German -in). The form of the English word may be via French caféine.

Online Etymology Dictionary, © 2010 Douglas Harper
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caffeine in Medicine

caffeine caf·feine or caf·fein (kā-fēn', kāf'ēn', kāf'ē-ĭn)
A bitter white alkaloid often derived from tea or coffee and used chiefly as a mild stimulant and in the treatment of certain kinds of headache.

The American Heritage® Stedman's Medical Dictionary
Copyright © 2002, 2001, 1995 by Houghton Mifflin Company. Published by Houghton Mifflin Company.
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caffeine in Science
A bitter white alkaloid found in tea leaves, coffee beans, and various other plant parts. It is a mild stimulant. Caffeine is a xanthine and similar in structure to theobromine and theophylline. Chemical formula: C8H10N4O2.
The American Heritage® Science Dictionary
Copyright © 2002. Published by Houghton Mifflin. All rights reserved.
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