1. A bitter crystallizable substance obtained from coffee.

Nuttall's Standard dictionary of the English language By Nuttall, P.Austin

• caffien,
• cafeine,
• caffen,
• caffine,
• caffene,
• caffin,
• coffein,
• xaffein,
• vaffein,
• faffein,
• daffein,
• czffein,
• csffein,
• cwffein,
• cqffein,
• cadfein,
• cacfein,
• cavfein,
• cagfein,
• catfein

• caffeine,
• cabin,
• coffin,
• Cuffing,
• cave-in,
• cavern,
• cave in,
• Cavin.

The adjective form of the word "caffein" is "caffeinated".

The plural of the "caffein" can be the "caffeins".

The singular of the "caffein" can be the "caffein".