Pronunciation: (mil'stōn"), [key]
1. either of a pair of circular stones between which grain or another substance is ground, as in a mill.
2. anything that grinds or crushes.
3. any heavy mental or emotional burden (often used in the phrase a millstone around one's neck).
Random House Unabridged Dictionary, Copyright © 1997, by Random House, Inc., on Infoplease.