Definition of hadal in English:

hadal

adjective

  • Relating to the zone of the sea greater than approximately 20,000 feet (6,000 m) in depth (chiefly oceanic trenches)

    • ‘Submarine trenches usually develop downward from depths around 6,000 m, the beginning of the hadal region, exclusive domain of highly specialized and exquisite molluscan communities.’
    • ‘The hadal environment (water depths greater than 6000m) is one of the last habitats on earth to be impacted by unsustainable human activity.’
    • ‘The hadal zone makes up only 1 or 2 percent of the ocean and is located in narrow oceanic trenches.’

Origin

Mid 20th century: from Hades + -al.

Pronunciation:

hadal

/ˈhādl/