"Astringent" is a tasting term used to describe a wine that makes your mouth feel dry and puckery, as if you're sipping absurdly strong tea. Astringency is a result of the excess tannins and/or high acidity common in young red wines, particularly those from Tuscany and Piedmont. In moderate amounts, astringency adds to a wine's complexity, preventing it from being dull and bland. Too much astringency, however, makes for a harsh, unenjoyable wine. To mellow out an overly astringent wine, either let it age longer or, if you've already popped the cork, try letting it breathe for an hour.