: 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
Players tend to take on longer lasting sources of energy, but reaching for a quickfire caffeine or sugar hit in times of need is not unheard of and the psychological impact of feeling energized can be just as important as any actual boost.
—
Ava Wallace, New York Times, 18 May 2026
Like chocolate, products that contain caffeine are a big no-no for animals of all sorts.
—Lauren Landers, Better Homes & Gardens, 17 May 2026
Women and men who notched higher caffeine intake had an 18% lower risk of dementia compared with people who drank little or no caffeine.
—Helen Carefoot, Flow Space, 15 May 2026
Lifestyle interventions include fans, limiting alcohol and caffeine, improving your sleep habits, exercising, managing stress, and quitting smoking.
—Kara Smythe, EverydayHealth.com, 15 May 2026
See All Example Sentences for caffeine
Examples are automatically compiled from online sources to
show current usage.
Read More
Opinions expressed in the examples do not represent those of Merriam-Webster or its editors.
Send us feedback.
Ava Wallace, New York Times, 18 May 2026
Like chocolate, products that contain caffeine are a big no-no for animals of all sorts.
—Lauren Landers, Better Homes & Gardens, 17 May 2026
Women and men who notched higher caffeine intake had an 18% lower risk of dementia compared with people who drank little or no caffeine.
—Helen Carefoot, Flow Space, 15 May 2026
Lifestyle interventions include fans, limiting alcohol and caffeine, improving your sleep habits, exercising, managing stress, and quitting smoking.
—Kara Smythe, EverydayHealth.com, 15 May 2026
See All Example Sentences for caffeine
Cite this Entry
“Caffeine.” Merriam-Webster.com Dictionary, Merriam-Webster, https://www.merriam-webster.com/dictionary/caffeine. Accessed 21 May. 2026.
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
Love words? Need even more definitions?
Merriam-Webster unabridged
