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Definition of "caffeine" []

  • A bitter white alkaloid, C8H10N4O2, often derived from tea or coffee and used in medicine chiefly as a mild stimulant and to treat certain kinds of headache. (noun)
  • A white crystalline bitter alkaloid responsible for the stimulant action of tea, coffee, and cocoa: a constituent of many tonics and analgesics. Formula: C8H10N4O2 (noun)

American Heritage(R) Dictionary of the English Language, Fifth Edition. Copyright (c) 2011 by Houghton Mifflin Harcourt Publishing Company. Published by Houghton Mifflin Harcourt Publishing Company. All rights reserved.

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Use "caffeine" in a sentence
  • "While none of the participants were given a drink high in caffeine, the researchers concluded that caffeine is probably more helpful than sugar in staying alert."
  • "After oil, caffeine is the biggest driver of our economy."
  • "No caffeine is allowed on the day of the exam, before the test is completed."