deposit
The sediment that settles in the bottle as a wine ages. Such deposits occur in many red wines and occasionally in some whites. It’s a natural process and doesn’t signify that there’s anything wrong with the wine.
The New Wine Lovers Companion, 2nd Edition, by Ron Herbst and Sharon Tyler Herbst. Copyright © (1) 2003, 1995 by Ron Herbst and Sharon Tyler Herbst. Reprinted by arrangement with Barron's Educational Series, Inc.