adj.
Of or relating to the deepest regions of the ocean, below about 6,000 meters (20,000 feet).
[French, from Hadès, Hades, from Greek Haidēs.]
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.
