caffeine
noun
caf·feine
| \ ka-ˈfēn
, ˈka-ˌfēn\
, ˈka-ˌfēn\
Definition of caffeine
: a bitter alkaloid C8H10N4O2 found especially in coffee, tea, cacao, and kola nuts and used medicinally as a stimulant and diuretic
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Examples of caffeine in a Sentence
Her doctor told her to avoid caffeine.
Recent Examples on the Web
The same effect as putting caffeine in the municipal drinking water. — Peter Hartlaub, SFChronicle.com, "Renel Brooks-Moon was born for this; SF Giants announcer has her father’s voice," 19 Aug. 2019 Tuello handed her a cup of coffee, just one human in a free, caffeine-permitting country to another, and the ordinariness of it—the banality, maybe—felt somehow obscene. — Sophie Gilbert, The Atlantic, "When Women Are Accused of Complicity," 17 Aug. 2019 Need a caffeine boost before that 7 a.m. class or a place to pull your first all-nighter? — Danielle Woodward, azcentral, "Everything you need to know about going to college in metro Phoenix. Seriously, everything," 17 Aug. 2019 The cucumber juice and the cold temperature act as anti-inflammatory compresses while the caffeine in the teabag will decrease fluid and improve circulation under the eyes. — Vogue, "How to Get Rid of Under Eye Bags," 16 Aug. 2019 And yet Williams was clearly more concerned with getting her caffeine juice. — Dan Gartland, SI.com, "Venus Williams Ordered a Cup of Coffee in the Middle of a Match," 15 Aug. 2019 Those who are vata dominant should minimize cold and raw foods and too much caffeine. — Cynthia Sass, Mph, Health.com, "What Is the Ayurvedic Diet—and Can It Help You Lose Weight?," 12 Aug. 2019 Unlike caffeine, alcohol and nicotine within four hours of bedtime did affect how well people slept. — Linda Carroll, NBC News, "An extra cup of coffee could up the odds of a migraine," 8 Aug. 2019 Running a start-up, late nights can often mesh into early mornings and caffeine is a must. — Allure, "Sunday Scaries Just Launched CBD-Infused Energy Shots," 7 Aug. 2019These example sentences are selected automatically from various online news sources to reflect current usage of the word 'caffeine.' Views expressed in the examples do not represent the opinion of Merriam-Webster or its editors. Send us feedback.
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More Definitions for caffeine
caffeine
noun
English Language Learners Definition of caffeine
: a substance that is found especially in coffee and tea and that makes you feel more awake
See the full definition for caffeine in the English Language Learners Dictionary
caffeine
noun
caf·feine
| \ ka-ˈfēn
, ˈka-ˌfēn\
, ˈka-ˌfēn\
Kids Definition of caffeine
: a substance found especially in coffee and tea that makes a person feel more awake
caffeine
noun
caf·feine
| \ ka-ˈfēn, ˈka-ˌ; ˈkaf-ē-ən
\
\
Medical Definition of caffeine
: a bitter alkaloid C8H10N4O2 found especially in coffee, tea, and kola nuts and used medicinally as a stimulant and diuretic
Other Words from caffeine
caffeinic
\ ka-ˈfē-nik
, ˌkaf-ē-ˈin-ik
\
adjective
, ˌkaf-ē-ˈin-ik
\
adjective
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