hadal

American  

[heyd-l] / ˈheɪd l /

adjective

Oceanography.

1. of or relating to the greatest ocean depths, below approximately 20,000 feet (6,500 meters).

2. of or relating to the biogeographic region of the ocean bottom below the abyssal zone.

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hadal British  

/ ˈheɪdəl /

adjective

1. of, relating to, or constituting the zones of the oceans deeper than abyssal: below about 6000 metres (18 000 ft) See also abyssal

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hadal Scientific  

/ hād′l /

1. Relating to the deepest regions of the ocean, below about 6,000 m (19,680 ft). The hadal zone mostly comprises trenches that can reach depths greater than 10,000 m (32,800 ft).

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Etymology

Origin of hadal

First recorded in 1955–60; Had(es) + -al ¹

Example Sentences

Finally, there are the incredibly deep seafloor trenches known as the hadal zone, named after Hades, Greek god of the underworld.

From Scientific American • Aug. 6, 2022

Since then, Dr Cui has set his eyes on the hadal zone in general, and in particular on the bottom of the Mariana trench.

From Economist • Aug. 25, 2016

Among other things, the institute hoped to use the robot, which was a ‘hybrid’ capable of being controlled remotely and operating autonomously, to investigate the ocean’s hadal zone.

From Nature • Dec. 8, 2015

We believe this will provide the operators with the best possible illusion of being in the deep ocean—without exposing them to the great risks of diving to hadal depths.

From Slate • Nov. 23, 2014

"The hadal zone is 45% of the ocean's depth range. So the entire discipline of deep sea biology has concentrated on the shallowest 50% and that seems wrong," he said.

From BBC • Jul. 16, 2014