tannin (n.) Look up tannin at Dictionary.com
"tannic acid, vegetable substance capable of converting animal hide to leather," 1802, from French tannin (1798), from tan "crushed oak bark containing tannin" (see tan (v.)). Tannic acid first recorded 1836, from French acide tannique, inroduced 1834 by French chemist Théophile-Jules Pelouze (1807-1867).