: 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
There are symptomatic fixes, sure—limiting caffeine and alcohol, the use of masking sounds—but there is no cure.
—
The New Yorker, New Yorker, 2 June 2025
Because smoking, caffeine and alcohol have been associated with bruxism, scaling back or cutting out these habits could help manage bruxism, says Kurup.
—Caroline C. Boyle, USA Today, 1 June 2025
As a result, cutting back or avoiding caffeine and alcohol can ease symptoms.
—Korin Miller, Flow Space, 30 May 2025
For many professionals, the answer is late nights, caffeine and sheer willpower.
—Bronwen Sciortino, Forbes.com, 28 May 2025
See All Example Sentences for caffeine
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The New Yorker, New Yorker, 2 June 2025
Because smoking, caffeine and alcohol have been associated with bruxism, scaling back or cutting out these habits could help manage bruxism, says Kurup.
—Caroline C. Boyle, USA Today, 1 June 2025
As a result, cutting back or avoiding caffeine and alcohol can ease symptoms.
—Korin Miller, Flow Space, 30 May 2025
For many professionals, the answer is late nights, caffeine and sheer willpower.
—Bronwen Sciortino, Forbes.com, 28 May 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 6 Jun. 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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