abyssal

[ uh-bis-uh l ]
/ əˈbɪs əl /

adjective

of or like an abyss; immeasurable; unfathomable.
of or relating to the biogeographic zone of the ocean bottom between the bathyal and hadal zones: from depths of approximately 13,000 to 21,000 feet (4000 to 6500 meters).

Origin of abyssal

From the Medieval Latin word abyssālis, dating back to 1685–95. See abyss, -al1
Dictionary.com Unabridged Based on the Random House Unabridged Dictionary, © Random House, Inc. 2019

Examples from the Web for abyssal

British Dictionary definitions for abyssal

abyssal

/ (əˈbɪsəl) /

adjective

of or belonging to the ocean depths, esp below 2000 metres (6500 feet)abyssal zone
geology another word for plutonic
Collins English Dictionary - Complete & Unabridged 2012 Digital Edition © William Collins Sons & Co. Ltd. 1979, 1986 © HarperCollins Publishers 1998, 2000, 2003, 2005, 2006, 2007, 2009, 2012

Science definitions for abyssal

abyssal

[ ə-bĭsəl ]

Relating to the greatest depths of the oceans and to the organisms that live there. The abyssal zone encompasses all depths below 4,000 m (13,120 ft).
Relating to the region of the ocean bottom between the bathyal and hadal zones, from depths of approximately 2,000 to 6,000 m (6,560 to 19,680 ft). The abyssal zone includes nearly two-thirds of the Earth's surface.
The American Heritage® Science Dictionary Copyright © 2011. Published by Houghton Mifflin Harcourt Publishing Company. All rights reserved.