monstrous sea creature symbolizing evil in the Old Testament the largest or most massive thing of its kind; "it was a leviathan among redwoods"; "they were assigned the leviathan of textbooks
{i} sea monster (Biblical); extremely large animal (especially a whale); something which is extremely large (especially a ship)
A leviathan is something which is extremely large and difficult to control, and which you find rather frightening. Democracy survived the Civil War and the developing industrial leviathan and struggled on into the twentieth century