crust
Another name for the sediment thrown off by red wines as they age in bottles. The use of the term crust is generally associated with vintage port (see port).
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.