noun
(biblical, mythology) A vast sea monster of tremendous strength, either imaginary or real, described as the most dangerous and powerful creature in the ocean.
A thing which is monstrously great in size, strength, etc. (especially a ship); also, a person with great power or wealth.
Sometimes in the form Leviathan: based on the writings of Thomas Hobbes, the political state, especially a domineering and totalitarian one.
Synonym of Satan (“the supreme evil spirit in the Abrahamic religions, who tempts humanity into sin; the Devil”).
adjective
Very large; enormous, gargantuan.