caffeine

caf·feine

noun \ka-ˈfēn, ˈka-ˌ; ˈkaf-ē-ən\

Definition of CAFFEINE

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

—caf·fein·ic \ka-ˈfē-nik, ˌkaf-ē-ˈin-ik\ adjective