Pronunciation: (up-hē'vul), [key]
1. strong or violent change or disturbance, as in a society: the upheaval of war.
2. an act of upheaving, esp. of a part of the earth's crust.
3. the state of being upheaved.
4. Geol.an upward warping of a part of the earth's crust, forcing certain areas into a relatively higher position than before.
Random House Unabridged Dictionary, Copyright © 1997, by Random House, Inc., on Infoplease.