caffeine

American  

[ka-feen, kaf-een, kaf-ee-in] / kæˈfin, ˈkæf in, ˈkæf i ɪn /

Rarely caffein

noun

1. Chemistry, Pharmacology. a white, crystalline, bitter alkaloid, C 8 H 10 N 4 O 2 , usually derived from coffee or tea: used in medicine chiefly as a nervous system stimulant.

2. Informal. a drink, usually coffee or tea, containing this stimulant.

   We sipped our caffeine on the balcony with its views of sea stacks, rocky coves, and the ever-changing ocean.

---

caffeine British  

/ ˈkæfiːn, ˈkæfɪˌiːn /

noun

1. a white crystalline bitter alkaloid responsible for the stimulant action of tea, coffee, and cocoa: a constituent of many tonics and analgesics. Formula: C 8 H 10 N 4 O 2 See also xanthine

---

caffeine Scientific  

/ kă-fēn′ /

1. A bitter white alkaloid found in tea leaves, coffee beans, and various other plant parts. It is a mild stimulant. Caffeine is a xanthine and similar in structure to theobromine and theophylline. Chemical formula: C ₈ H ₁₀ N ₄ O ₂ .

---

Other Word Forms

• noncaffeine
  noun
• caffeinic
  adjective
• noncaffeinic
  adjective

---

Etymology

Origin of caffeine

First recorded in 1820–30; from French caféine, equivalent to café coffee + -ine -ine ²

---

Compare meaning

How does caffeine compare to similar and commonly confused words? Explore the most common comparisons:

• theobromine vs. caffeine

---

Explanation

Good morning! Caffeine keeps you awake! It’s that zippy chemical found in coffee, tea, and sodas. In fact, it comes from the German word for “coffee.” Caffeine is a chemical found naturally in the seeds of some fruits and nuts, like coffee beans and kola nuts. It’s a stimulant, so it makes people feel alert. People love to start their mornings with coffee to help them perk up for the day. The word comes from the German Kaffein, coined in 1830 by a chemist who combined the word for "coffee," Kaffee, with -in, a German chemical suffix.

Example Sentences

See Examples For:

caffeine

"All high-caffeine beverages carry a 'not recommended for children' label. The available evidence shows that the vast majority of caffeine consumed by children and adolescents comes from sources other than energy drinks."

From BBC ● Nov. 6, 2026

If the measurement is higher or lower than “ideal,” the app provides a short blurb about what that could mean, like I could have slept poorly or had too much caffeine.

From Slate ● Oct. 9, 2026

The functional food trend is pushing caffeine where protein went before it, into a range of packaged foods and drinks from beef jerky to water.

From The Wall Street Journal ● Oct. 7, 2026

Participants completed psychological assessments and kept records of caffeine intake and diet.

From Science Daily ● Sep. 28, 2026

Yaupon holly was the only plant indigenous to this land that contained caffeine.

From "Legendary Frybread Drive-In" by Cynthia Leitich Smith

Random Word

Spin the wheel and learn a new word!

---

Related Words

• cappuccino
• espresso

---