(n.) A white, bitter, crystallizable substance, obtained from coffee. It is identical with the alkaloid theine from tea leaves, and with guaranine from guarana.
Webster's Revised Unabridged Dictionary
| APA | Webster's. (2011). caffeine. Retrieved September 22, 2026, from http://smartdefine.org/caffeine/definitions/1983725 |
| Chicago | Webster's. 2011. "caffeine" http://smartdefine.org/caffeine/definitions/1983725 (accessed September 22, 2026). |
| Harvard | Webster's 2011, caffeine, Smart Define, viewed 22 September, 2026, <http://smartdefine.org/caffeine/definitions/1983725>. |
| MLA | Webster's. "caffeine" 27 May 2011. Web. 22 September 2026. <http://smartdefine.org/caffeine/definitions/1983725> |