Pronunciation: (un-stop'), [key]
—v.t., -stopped, -stop•ping.
1. to remove the stopper from: to unstop a bottle.
2. to free from any obstruction; open: to unstop a sewer.
3. to draw out the stops of (an organ).
Random House Unabridged Dictionary, Copyright © 1997, by Random House, Inc., on Infoplease.