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Definitions

caffeine

[ka-feen, kaf-een, kaf-ee-in] / kæˈfin, ˈkæf in, ˈkæf i ɪn /
NOUN
coffee
Synonyms
STRONGEST
cappuccino espresso
STRONG
brew decaf decoction demitasse ink java mocha mud perk
WEAK
battery acid café café au lait café noir forty weight hot stuff jamocha joe varnish remover

Example Sentences

Examples are provided to illustrate real-world usage of words in context. Any opinions expressed do not reflect the views of Dictionary.com.

These results suggest that coffee can enhance mood even without caffeine.

From Science Daily • May 3, 2026

Only participants consuming caffeine experienced reduced anxiety along with better attention and alertness.

From Science Daily • May 3, 2026

There, they encountered a drop of sugar solution containing 0, 25 ppm, 250 ppm, or 2,000 ppm of caffeine.

From Science Daily • Apr. 18, 2026

The research team explored whether caffeine, which is already known to enhance learning in bees, could help ants better remember bait locations and lead more nestmates to them.

From Science Daily • Apr. 18, 2026

“Run along now and have your cup of caffeine solution, dear,” she said to the other nurse.

From "Brave New World" by Aldous Huxley