Pronunciation: (sil), [key]
1. a horizontal timber, block, or the like serving as a foundation of a wall, house, etc.
2. the horizontal piece or member beneath a window, door, or other opening. See diag. under double-hung.
3. Geol.a tabular body of intrusive igneous rock, ordinarily between beds of sedimentary rocks or layers of volcanic ejecta.
Random House Unabridged Dictionary, Copyright © 1997, by Random House, Inc., on Infoplease.