designating or of the ecological zone (hadal zone) of the ocean floor trenches below c. 19,685 ft (c. 6,000 m)
Origin of hadalFrench ; from Hadès, Hades + -al, -al
Of or relating to the deepest regions of the ocean, below about 6,000 meters (20,000 feet).
Origin of hadalFrench, from Hadès, Hades, from Greek Haid&emacron;s; see weid- in Indo-European roots.
From French hadal, from Hadès + -al.