caffeine

noun
caf·​feine | \ ka-ˈfēn How to pronounce caffeine (audio) , ˈka-ˌfēn\

Definition of caffeine

: a bitter alkaloid C8H10N4O2 found especially in coffee, tea, cacao, and kola nuts and used medicinally as a stimulant and diuretic

Keep scrolling for more

Examples of caffeine in a Sentence

Her doctor told her to avoid caffeine.

Recent Examples on the Web

Some of us are quick to metabolize an after-dinner espresso; others swear off caffeine after noon. Laura Regensdorf, Vogue, "How to Get a Better Night’s Sleep—And Why It Should Be Your Top Priority (Really)," 1 Nov. 2018 This natural beauty pick has some major de-puffing powers — the caffeine in its formula shrinks puffy morning eyes in a matter of a minute (Allure editors can attest to this). Tanisha Pina, Allure, "13 Beauty Essentials You Should Stock Up On During Amazon Prime Day," 16 July 2018 In 2010, Four Loko nixed the caffeine from its recipe. Sean Rossman, USA TODAY, "A sangria so potent, it reminds drinkers of Four Loko," 17 May 2018 The supermodel, who alongside her husband Tom Brady follows a strict no-white sugar, no-white flour, no-MSG, no-caffeine, no-fungus, no-dairy diet, told WSJ. Ana Calderone, PEOPLE.com, "Gisele Bündchen's 'Guilty Pleasure' Food Is 10 Dunkin' Donuts Munchkins—Yes, Really," 27 Mar. 2018 Ruggiero says that the caffeine in coffee works to narrow the swollen blood vessels in your head, elevating your pain. Lori Keong, Marie Claire, "10 Expert-Approved Secrets to Hack Your Hangover," 12 Dec. 2016 These are likely due to certain compounds in coffee but may also be partially because of the caffeine. Tori Rodriguez, Woman's Day, "5 "Bad" Habits That Are Actually Good for You," 3 Aug. 2016 Your caffeine and alcohol intake can be major players. Carolyn L. Todd, SELF, "How Much Sleep Do I Need?," 21 Mar. 2019 That makes sense since the caffeine in it is, of course, energizing! Jaclyn London, Ms, Rd, Cdn, Good Housekeeping, "Keto Diet Pills and Supplements May Hurt Your Health and Waste Your Money," 16 Jan. 2019

These example sentences are selected automatically from various online news sources to reflect current usage of the word 'caffeine.' Views expressed in the examples do not represent the opinion of Merriam-Webster or its editors. Send us feedback.

See More

First Known Use of caffeine

circa 1823, in the meaning defined above

History and Etymology for caffeine

German Kaffein, from Kaffee coffee, from French café

Keep scrolling for more

Learn More about caffeine

Statistics for caffeine

Last Updated

22 Apr 2019

Look-up Popularity

Time Traveler for caffeine

The first known use of caffeine was circa 1823

See more words from the same year

Keep scrolling for more

More Definitions for caffeine

caffeine

noun

English Language Learners Definition of caffeine

: a substance that is found especially in coffee and tea and that makes you feel more awake

caffeine

noun
caf·​feine | \ ka-ˈfēn How to pronounce caffeine (audio) , ˈka-ˌfēn\

Kids Definition of caffeine

: a substance found especially in coffee and tea that makes a person feel more awake

caffeine

noun
caf·​feine | \ ka-ˈfēn, ˈka-ˌ; ˈkaf-ē-ən How to pronounce caffeine (audio) \

Medical Definition of caffeine

: a bitter alkaloid C8H10N4O2 found especially in coffee, tea, and kola nuts and used medicinally as a stimulant and diuretic

Other Words from caffeine

caffeinic \ ka-​ˈfē-​nik How to pronounce caffeinic (audio) , ˌkaf-​ē-​ˈin-​ik How to pronounce caffeinic (audio) \ adjective

Keep scrolling for more

More from Merriam-Webster on caffeine

Rhyming Dictionary: Words that rhyme with caffeine

Spanish Central: Translation of caffeine

Nglish: Translation of caffeine for Spanish Speakers

Britannica English: Translation of caffeine for Arabic Speakers

Britannica.com: Encyclopedia article about caffeine

Comments on caffeine

What made you want to look up caffeine? Please tell us where you read or heard it (including the quote, if possible).

WORD OF THE DAY

not to be persuaded, moved, or stopped

Get Word of the Day daily email!

Test Your Vocabulary

Words from Greek and Latin Quiz

  • roman forum
  • Which of the following months comes from a Latin word for “ten”?
How Strong Is Your Vocabulary?

Test your vocabulary with our 10-question quiz!

TAKE THE QUIZ
SCRABBLE® Sprint

Test Your Knowledge - and learn some interesting things along the way.

TAKE THE QUIZ
Love words? Need even more definitions?

Subscribe to America's largest dictionary and get thousands more definitions and advanced search—ad free!