Pronunciation: (im-pas'u-bul, -pä'su-), [key]
1. not passable; not allowing passage over, through, along, etc.: Heavy snow made the roads impassable.
2. unable to be surmounted: an impassable obstacle to further negotiations.
3. (of currency) unable to be circulated: He tore the bill in half, making it impassable.
Random House Unabridged Dictionary, Copyright © 1997, by Random House, Inc., on Infoplease.