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: a bitter alkaloid C8H10N4O2 found especially in coffee, tea, cacao, and kola nuts and used medicinally as a stimulant and diuretic
Examples of caffeine in a Sentence
Her doctor told her to avoid caffeine.
Recent Examples on the Web
The fermentation process in kombucha creates tyramine—a compound that stimulates your nervous system—and trace amounts of caffeine.
—Bryan Robinson, Forbes, 7 Dec. 2024
Post-pandemic, people want natural foods that can support their immune systems, clear their heads and boost their energy without caffeine jitters.
—Robert Johnson, Rolling Stone, 6 Dec. 2024
In this formulation, caffeine constricts blood vessels to reduce puffiness and dark circles, while Caudalie’s patented ingredient, Viniferine is a natural compound derived from grapevine sap and stalks, to help reduce hyperpigmentation by inhibiting melanin production.
—Conçetta Ciarlo, Vogue, 2 Dec. 2024
Many causes of tachycardia, such as consuming too much caffeine, are easy to change, while other causes can include underlying problems with your heart or other organs.
—Anna Giorgi, Verywell Health, 29 Nov. 2024
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Word History
Etymology
German Kaffein, from Kaffee coffee, from French café
First Known Use
circa 1823, in the meaning defined above
Phrases Containing caffeine
Dictionary Entries Near caffeine
Cite this Entry
“Caffeine.” Merriam-Webster.com Dictionary, Merriam-Webster, https://www.merriam-webster.com/dictionary/caffeine. Accessed 25 Dec. 2024.
Kids Definition
caffeine
noun
caf·feine
ka-ˈfēn
ˈka-ˌfēn
: a bitter stimulating compound found especially in coffee, tea, cacao, and kola nuts
Medical Definition
caffeine
noun
caf·feine
ka-ˈfēn, ˈka-ˌ; ˈkaf-ē-ən
: a bitter alkaloid C8H10N4O2 found especially in coffee, tea, and kola nuts and used medicinally as a stimulant and diuretic
More from Merriam-Webster on caffeine
Nglish: Translation of caffeine for Spanish Speakers
Britannica English: Translation of caffeine for Arabic Speakers
Britannica.com: Encyclopedia article about caffeine
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