Artificial intelligent assistant

abyssal

abyssal, a.
  (əˈbɪsəl)
  [ad. late L. abyssāl-is of or belonging to an abyss, f. abyss-us; see abyss and -al1.]
  Of unsearchable depth, unfathomable; belonging to the lowest depths of ocean. abyssal zone, the bottom strata of the sea, the belt of water below 300 fathoms.

1691 Behmen Theosoph. Philos. 42 Whose immensity is Abyssal. 1752 W. Law Spir. of Love (1816) ii. 66 God is an abyssal infinity of love, wisdom, & goodness. 1830 Lyell Princ. Geol. (1875) II. iii. xlix. 589 The Coral fauna of the deep and abyssal sea. 1872 Nicholson Palæont. 23 The abyssal mud of the Atlantic is to a very large extent composed of the microscopic shells of Foraminifera.

Oxford English Dictionary

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