Noun: caffeine ka'feen or 'ka,feen [N. Amer], 'ka,feen [Brit]
- A bitter alkaloid found in coffee and tea, responsible for their stimulating effects
"She avoided caffeine in the evening to improve her sleep"
Derived forms: caffeines
Type of: alkaloid
Part of: cha [Brit, informal], char [Brit, informal], coffee, java [N. Amer, informal], joe [N. Amer, informal], tea
Encyclopedia: Caffeine