: 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
Energy drinks are designed to boost energy levels via caffeine and other stimulants, such as glucose.
—
Laura Dorwart, Verywell Health, 4 Apr. 2025
If your acne extends to your undereyes, this is an excellent pick, as vitamin E and caffeine can help cut down on puffiness and dark circles that underscore your zits.
—Annie Blackman, Allure, 4 Apr. 2025
In a lawsuit, her family said Katz had a heart condition and intentionally avoided caffeine, accusing Panera of misleading marketing and inadequate labeling that led to Katz unknowingly consuming 390 mg - more caffeine than is in a typical energy drink.
—Mary Walrath-Holdridge, USA Today, 3 Apr. 2025
The myriad things that influence human behavior, such as caffeine, genetic diseases, or a happy childhood, constitute evidence that people are affected by many different kinds of things, not that these things determine their behavior.
—Jessica Riskin, The New York Review of Books, 3 Apr. 2025
See All Example Sentences for caffeine
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Laura Dorwart, Verywell Health, 4 Apr. 2025
If your acne extends to your undereyes, this is an excellent pick, as vitamin E and caffeine can help cut down on puffiness and dark circles that underscore your zits.
—Annie Blackman, Allure, 4 Apr. 2025
In a lawsuit, her family said Katz had a heart condition and intentionally avoided caffeine, accusing Panera of misleading marketing and inadequate labeling that led to Katz unknowingly consuming 390 mg - more caffeine than is in a typical energy drink.
—Mary Walrath-Holdridge, USA Today, 3 Apr. 2025
The myriad things that influence human behavior, such as caffeine, genetic diseases, or a happy childhood, constitute evidence that people are affected by many different kinds of things, not that these things determine their behavior.
—Jessica Riskin, The New York Review of Books, 3 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 10 Apr. 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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