tannin tanniferous • tannin color · · · Info · Definitions · Synonyms · Characters · · tannin · · Text Latin · · Script 6 · · Length 2 · · Syllables Definitions · · · (noun) any of various complex phenolic substances of plant origin; used in tanning and in medicine. Synonyms: tannic acid. · · Noun Definition 1 Synonyms · · · tannic acid · · Synonym 1 Characters · · a latin small letter a U+0061 i latin small letter i U+0069 n latin small letter n U+006E t latin small letter t U+0074