Definitions

1. adjective

relating to or found in the deepest part of the ocean, especially the area of the ocean floor below about 20,000 feet (6,000 meters) where the light from the sun does not penetrate.

“The team of scientists studied the abyssal zone of the Mariana Trench.”

2. noun

the lowest or deepest part of something, especially the ocean.

“The abyssal plains of the ocean are vast and unexplored areas.”

3. adverb

to a great depth or extent.

“The water was abyssally cold in the lake.”