: 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
Key Ingredients: Ginseng, peptides, caffeine, squalane Best For: Skin laxity, fine lines, wrinkles, dark circles
Size: 0.5 oz.
—
Emily Orofino, Vogue, 23 Oct. 2024
Contrary to popular belief, Pink Cocaine does not contain cocaine but is instead a combination of 2-CB, MDMA (ecstasy), ketamine, and caffeine according to the National Capital Poison Center.
—Lea Veloso, StyleCaster, 22 Oct. 2024
Today, drugs already exist to help with e.g. alertness or focus (caffeine, modafinil, ritalin) but as with many other previous areas, much more is likely to be possible.
—John Werner, Forbes, 14 Oct. 2024
Warrier said there are an array of factors that can lead to the condition, including excessive stress and caffeine consumption, as well as structural issues of the heart.
—Sam Farmer, Los Angeles Times, 14 Oct. 2024
See all Example Sentences for caffeine 
Emily Orofino, Vogue, 23 Oct. 2024
Contrary to popular belief, Pink Cocaine does not contain cocaine but is instead a combination of 2-CB, MDMA (ecstasy), ketamine, and caffeine according to the National Capital Poison Center.
—Lea Veloso, StyleCaster, 22 Oct. 2024
Today, drugs already exist to help with e.g. alertness or focus (caffeine, modafinil, ritalin) but as with many other previous areas, much more is likely to be possible.
—John Werner, Forbes, 14 Oct. 2024
Warrier said there are an array of factors that can lead to the condition, including excessive stress and caffeine consumption, as well as structural issues of the heart.
—Sam Farmer, Los Angeles Times, 14 Oct. 2024
See all Example Sentences for caffeine
These examples are programmatically compiled from various online sources to illustrate current usage of the word 'caffeine.' Any opinions expressed in the examples do not represent those of Merriam-Webster or its editors. Send us feedback about these examples.
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Cite this Entry
“Caffeine.” Merriam-Webster.com Dictionary, Merriam-Webster, https://www.merriam-webster.com/dictionary/caffeine. Accessed 5 Nov. 2024.
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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