caffeine

noun

caf·​feine ka-ˈfēn How to pronounce caffeine (audio)
ˈka-ˌfēn
: 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 oil-free formula is packed with ingredients like squalane and glycerin for moisture, and caffeine to brighten the skin, decrease puffiness, and soothe inflammation. Danielle Cohen, Glamour, 1 Mar. 2024 The limit actually does exist: Most adults should have no more than 400 milligrams of caffeine per day, according to the FDA. Li Goldstein, Bon Appétit, 23 Feb. 2024 This occurs when one's body becomes accustomed to caffeine and then doesn't get it for an extended period of time such as a full night's sleep. Daryl Austin, USA TODAY, 20 Feb. 2024 Studies also show that caffeine persists in the body for a long time, reducing sleep quality. Meimei Fox, Forbes, 15 Feb. 2024 While many blends also include coffee, mushroom coffee has far less caffeine than the regular cup of joe, but still promises to support energy and focus. Jenna Anderson, Sunset Magazine, 8 Feb. 2024 Dietary considerations: Avoiding caffeine, alcohol and heavy meals before sleep aids in restfulness. Joanna Fong-Isariyawongse, The Conversation, 31 Jan. 2024 The rules also would require packaging that doesn’t appeal to children and would prohibit marijuana from being infused into alcohol, nicotine or caffeine products. Peter Hecht, Sacramento Bee, 21 Feb. 2024 The formula is enriched with lots of impressive haircare ingredients such as plant collagen, caffeine, biotin, and niacinamide, which help replenish nutrients, repair damage, and restore hair health. Jessie Quinn, Peoplemag, 15 Feb. 2024

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.

Word History

Etymology

German Kaffein, from Kaffee coffee, from French café

First Known Use

circa 1823, in the meaning defined above

Time Traveler
The first known use of caffeine was circa 1823

Dictionary Entries Near caffeine

Cite this Entry

“Caffeine.” Merriam-Webster.com Dictionary, Merriam-Webster, https://www.merriam-webster.com/dictionary/caffeine. Accessed 18 Mar. 2024.

Kids Definition

caffeine

noun
caf·​feine ka-ˈfēn How to pronounce caffeine (audio)
ˈka-ˌfēn
: a bitter stimulating compound found especially in coffee, tea, cacao, and kola nuts

Medical Definition

caffeine

noun
: a bitter alkaloid C8H10N4O2 found especially in coffee, tea, and kola nuts and used medicinally as a stimulant and diuretic
caffeinic adjective

More from Merriam-Webster on caffeine

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