1. Geology. The doctrine that major changes in the earth's crust result from catastrophes rather than evolutionary processes.
2. The prediction or expectation of cataclysmic upheaval, as in political or social developments.

The American Heritage® Dictionary of the English Language, Fourth Edition Copyright © 2007, 2000 by Houghton Mifflin Company. Updated in 2009. Published by Houghton Mifflin Company. All rights reserved.