caffeine
US /kæˈfin, ˈkæfˌin, ˈkæfiɪn/
・UK /ˈkæfi:n/
B2
noun
- Substance in coffee, etc. that keeps you awake
other
- The quantity of caffeine consumed.
- The stimulating effect produced by caffeine.
- A stimulant drug found in coffee, tea, and some soft drinks.