Definitions for hadalˈheɪd l
Random House Webster's College Dictionary
of or pertaining to the biogeographic region of the ocean bottom below the abyssal zone, or from approximately 20,000 ft. (6500 m) to the greatest ocean depths.
Origin of hadal:
1955–60; Had (es ) + -al1
relating to the deepest parts of the ocean (below 6000 meters)
of, or relating to the deepest parts of the ocean
Origin: From hadal, from Hadès + -al.