hadal

[ heyd-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.

hadal

/ 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

hadal

/ 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).

Word History and Origins

Origin of hadal¹

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

Word History and Origins

Origin of hadal¹

C20: from French, from Hadés Hades

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

In studies, more than half of sampled hadal organisms—those living in the deepest parts of the ocean, beyond 20,000 feet—had plastics in their gut.

From Scientific American

The study authors captured hadal snailfish from about 7,000 metres down in the Mariana Trench in the western Pacific Ocean.

From Nature

This creature of the dark, frigid ocean region known as the hadal zone was first caught in 2014 and again early in 2017 but is only now being described.

From National Geographic

The hadal zone is one of the most poorly studied habitats on Earth.

From Nature