caffeine

UK/ˈkæfiːn/US/ˈkæfiːn/

nounB1+Common in everyday speech and writing · #4,830 of 15,258neutral

Caffeine is the substance in coffee and tea that keeps you awake. Too much caffeine, cut down on caffeine, caffeine content.

It works by blocking the chemical that tells the brain it is tired, so the tiredness is still there and arrives later. It has a half-life of about five hours, which is why an afternoon coffee costs sleep. It is the most widely used stimulant in the world.

Definitions of caffeine

1nouncaffeineThe stimulant found in coffee and tea.B1+
“I avoid drinking coffee in the evening because the caffeine keeps me awake.”

caffeine is a stimulant.

Where it comes from

French cafeine comes from cafe, coffee, from Arabic qahwa by way of Turkish.

Italian
caffè — coffee
German
Caffein
French
caféine
English, today
caffeine

Built from

café · French — coffee
Kaffee · German — coffee

French caféine, from café (“coffee”), or German Caffein, Kaffein (cp. Coffein, Koffein), from Kaffee (“coffee”) (cp. Kaffe, Koffee, Koffe), or Italian caffè (“coffee”) ine.

Etymology from Wiktionary, CC BY-SA

Practise this word

caffeine in the wild

The most common sources of caffeine for human consumption are the tea leaves of the Camellia sinensis plant and the coffee bean, the seed of the Coffea plant.
Caffeine
Around 80% of the world population consumes caffeine in one form or another.
Caffeine toxicity
Energy drinks have the effects of caffeine and sugar, but there is little or no evidence that the wide variety of other ingredients have any effect.
Energy drink
A caffeine content reduction of at least 97% is required under United States FDA standards.
Decaffeination
Some pills, like pain relievers, also contain caffeine.
Caffeine dependence

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From Wikipedia, CC BY-SA 4.0. These sentences were written by other people about their own subjects; they are here to show the word at work, not as anybody’s opinion.

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