1. a yellowish or brownish bitter-tasting organic substance found in certain plant tissues, especially bark and leaves, used in tanning leather and making ink
2. a compound that gives an astringent taste to wine, tea, or other beverages

Examples

• The oak bark contains high levels of tannin used for leather production.
• Red wine gets its dry taste from tannins in the grape skins.
• Tea that steeps too long becomes bitter due to excess tannin.
• The tannin in the acorns made them inedible without processing.
• Winemakers carefully manage tannin levels during fermentation.
• The leather industry relies on tannin extracted from tree bark.
• Some people are sensitive to the tannins in certain foods.