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

Cocoa powder contains a small amount of caffeine, around 12 milligrams per tablespoon. —Jillian Kubala, Health, 4 Nov. 2024

Abdur-Rahim frequently walked across campus to a coffee shop and the student center, and whoever happened to be there was treated to a dose of caffeine and perhaps donut or two. —Tom Layberger, Forbes, 3 Nov. 2024

Running on adrenaline and continuous infusions of caffeine, its analysts and data scientists were glued to their monitors around the clock, watching the slow trickle of results from Pennsylvania that ultimately would decide the race. —Josh Rottenberg, Los Angeles Times, 3 Nov. 2024

The small amounts of caffeine in chocolate are another risk, Hill's Pet Nutrition reports. —Olivia Munson, USA TODAY, 2 Nov. 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