Synonyms of 'leviathan'
If you refer to something as a behemoth, you mean that it is extremely large, and often that it is unpleasant, inefficient, or difficult to manage.
The city is a sprawling behemoth with no heart.
Thesaurus for leviathan from the Collins English Thesaurus
A leviathan is something which is extremely large and difficult to control, and which you find rather frightening .