caffeine

noun

caf·​feine ka-ˈfēn 

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

While that legacy business has flagged since those heydays, the addition of caffeine to his portfolio has perked things up. —Jonathan Burgos, Forbes, 5 Sep. 2024

For example, for an adult weighing 150 pounds (68 kg), that’s 204-408 mg of caffeine. —Cynthia Sass, Mph, Health, 3 Sep. 2024

Increasing your caffeine consumption to an equivalent of three to four cups of coffee per day can also help by increasing CSF production through stimulating the choroid plexus. —Danielle Wilhour, The Conversation, 14 Aug. 2024

The caffeine in coffee can ramp up muscle contractions in the colon that stimulate bowel movements. —Lori Youmshajekian, Scientific American, 13 Aug. 2024

Word History

Etymology

German Kaffein, from Kaffee coffee, from French café

First Known Use

circa 1823, in the meaning defined above

Phrases Containing caffeine

• caffeine-free

Kids 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

caffeinic

ka-ˈfē-nik  ˌkaf-ē-ˈin-ik 

adjective