1. a bitter white crystalline compound found in coffee, tea, and other plants that acts as a stimulant to the central nervous system

Examples

• I need my morning coffee for the caffeine boost.
• Green tea contains less caffeine than black coffee.
• She avoided caffeine after 3 PM to sleep better.
• The energy drink had 200 milligrams of caffeine.
• Chocolate contains small amounts of caffeine.
• He switched to decaf to reduce his caffeine intake.
• Too much caffeine can cause jitters and anxiety.