The Collaborative International Dictionary of English v.0.48:

Divide \Di*vide"\, n.
   A dividing ridge of land between the tributaries of two
   streams; also called watershed and water parting. A
   divide on either side of which the waters drain into two
   different oceans is called a continental divide.
   [1913 Webster +PJC]

WordNet (r) 3.0 (2006):

continental divide
    n 1: the watershed of a continent (especially the watershed of
         North America formed by a series of mountain ridges
         extending from Alaska to Mexico)