Pronunciation: (grīnd'stōn"), [key]
1. a rotating solid stone wheel used for sharpening, shaping, etc.
2. a millstone.
3. keep or put one's nose to the grindstone, to work, study, or practice hard and steadily or to cause someone to do so: If I put my nose to the grindstone, I'll finish the job this week.
Random House Unabridged Dictionary, Copyright © 1997, by Random House, Inc., on Infoplease.