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

The new additions will contain more caffeine than the original Refreshers, which give drinkers roughly the same boost as a caffeinated soda. —Amelia Lucas, CNBC, 29 Jan. 2026

Consuming more than 1,200 mg of caffeine per day may increase your risk of side effects. —Brittany Lubeck, Verywell Health, 29 Jan. 2026

Keurig Dr Pepper has recalled about 80,640 McCafe Premium Roast Decaf Coffee K-Cup Pods because the pods may contain caffeine, according to a Food & Drug Administration report. —Greta Cross, The Providence Journal, 29 Jan. 2026

The new version is based on its popular Refreshers drinks brand, and will derive its caffeine from green coffee extract, or unroasted coffee beans. —Jordan Valinsky, CNN Money, 29 Jan. 2026

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