continental slope

from The American Heritage® Dictionary of the English Language, 5th Edition.

• noun The steep slope descending from the continental shelf to the continental rise.

from Wiktionary, Creative Commons Attribution/Share-Alike License.

• noun geology The steep, narrow fringe separating the coastal zone from the deep ocean

from WordNet 3.0 Copyright 2006 by Princeton University. All rights reserved.

• noun the steep descent of the seabed from the continental shelf to the abyssal zone