1. The belief in or the policy of advancing toward a goal by gradual, often slow stages.
2. Biology. The view that speciation proceeds by imperceptibly small, cumulative steps over long periods of time rather than by abrupt, major changes.

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.