Dictionary
a•byss•al
Pronunciation: (u-bis'ul), [key]—
adj.
1. of or like an abyss; immeasurable; unfathomable.
2. of or pertaining to the biogeographic zone of the ocean bottom between the bathyal and hadal zones: from depths of approximately 13,000 to 21,000 ft. (4000 to 6500 m).
Random House Unabridged Dictionary, Copyright © 1997, by Random House, Inc., on Infoplease.