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

Caffeine content and limits: Because black and green tea contain caffeine, limit their consumption to fewer than 4 cups daily. —Melissa Nieves, Verywell Health, 21 May 2025

Even simple changes like daily walks, consistent meal times, and limiting caffeine can significantly improve your resilience during high-pressure periods. —Kara Dennison, Forbes.com, 20 May 2025

If there isn’t an underlying cause, lifestyle changes such as warm baths or massages, heat or cold packs, and avoiding caffeine can help. —The Washington Post, San Diego Union-Tribune, 20 May 2025

For some people, cutting out caffeine by late morning is best. —Malaka Gharib, NPR, 19 May 2025

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

Rhymes for caffeine

• agin
• alkene
• allene
• ameen
• amin
• amine
• arene
• athene
• baleen
• beeline
• benzene
• between

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