Dictionary
ha•dal
Pronunciation: (hād'l), [key]—
adj.
1. of or pertaining to the greatest ocean depths, below approximately 20,000 ft. (6500 m).
2. of or pertaining to the biogeographic region of the ocean bottom below the abyssal zone.
Random House Unabridged Dictionary, Copyright © 1997, by Random House, Inc., on Infoplease.