life zone definition by Webster's New World
Webster's New World College Dictionary Copyright © 2010 by Wiley Publishing, Inc., Cleveland, Ohio. Used by arrangement with John Wiley & Sons, Inc.
any of a series of biogeographic zones into which a continent, region, etc. is divided both by latitude and altitude on the basis of the characteristic animal and plant life in a zone
life zone definition by American Heritage Dictionary
A geographic region or area defined by its characteristic life forms.