"Leviathan is mentioned in Daniel Robinson's ‘Great Ideas of Philosophy,’ an audio recording of several lectures. In that context, I took the word to mean the overarching system of ideas, morals, rules of governance and the constraints and freedoms of any society at any giving time in history. The vast machine that is built with the sole intention of keeping us from anarchy and to halt the break down of said societies' version of humanity."
Roisin explaining the meaning of Leviathan to Billboard. You can read the full interview here.