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

What distinguishes an energy drink from other soft drinks is its high level of caffeine, along with additives like taurine (an amino acid), B-12 (a vitamin) and guarana extract (from an Amazonian fruit). —Jeffrey Gettleman, New York Times, 8 June 2024

Limit certain items: These include non-steroidal anti-inflammatory drugs (NSAIDs), alcohol, caffeine, antibiotics, and nutritional supplements, which can upset your stomach. —Laurel Leicht, Health, 1 June 2024

But too much caffeine can cause negative health effects. —Beth Ann Mayer, Parents, 24 May 2024

Unfortunately, some health experts are concerned that the process required to remove caffeine from the brew could be increasing people's risk of cancer. —Devika Rao, theweek, 21 May 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