: 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
For a caffeine fix — a necessity at any diner — there are mugs of $1 Cafe du Monde chicory coffee.
—
Stephanie Breijo, Los Angeles Times, 24 Apr. 2025
Additionally, combining cannabis with other substances, like caffeine, should be approached cautiously due to potential interactions.
—Matt Rozo, Mercury News, 23 Apr. 2025
Other foods that are toxic to cats, according to Preventive Vet, include milk and dairy; onions and garlic; alcohol; chocolate; grapes, raisins and currants; caffeine; raw meat; seafood; eggs; raw dough; avocado; and bones.
—Thomas G. Moukawsher, MSNBC Newsweek, 17 Apr. 2025
Perhaps the only exception was the coffee shop, where tables were often full by mid-morning as guests awaited their caffeine fix.
—David Nikel, Forbes.com, 7 Apr. 2025
See All Example Sentences for caffeine
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Stephanie Breijo, Los Angeles Times, 24 Apr. 2025
Additionally, combining cannabis with other substances, like caffeine, should be approached cautiously due to potential interactions.
—Matt Rozo, Mercury News, 23 Apr. 2025
Other foods that are toxic to cats, according to Preventive Vet, include milk and dairy; onions and garlic; alcohol; chocolate; grapes, raisins and currants; caffeine; raw meat; seafood; eggs; raw dough; avocado; and bones.
—Thomas G. Moukawsher, MSNBC Newsweek, 17 Apr. 2025
Perhaps the only exception was the coffee shop, where tables were often full by mid-morning as guests awaited their caffeine fix.
—David Nikel, Forbes.com, 7 Apr. 2025
See All Example Sentences for caffeine
Cite this Entry
“Caffeine.” Merriam-Webster.com Dictionary, Merriam-Webster, https://www.merriam-webster.com/dictionary/caffeine. Accessed 1 May. 2025.
Copy CitationKids 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
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