A bitter white alkaloid,C8H10N4O2,often derived from tea or coffee and used in medicine chiefly as a mild stimulant and to treat certain kinds of headache.

• 咖啡因一种苦味的白色生物碱，C8H10N4O2，通常得自咖啡或茶，在药品中主要作为温和兴奋剂及治疗特定的头痛病。