IPA: /ˈmɜːdə.rəs.nəs/
KK: /ˈmɜrdərəsnəs/
The quality or state of being inclined to commit murder or showing a desire to kill.
The film explored the murderousness of the villain, revealing his dark motivations.
Murderousness → It is formed from "murder" (from Old French *murder*, meaning the unlawful killing of a human being) and "-ous" (meaning full of) and "-ness" (meaning the state or quality of). The word "murderousness" refers to the quality or state of being full of murder or inclined to kill.
Think of the word 'murder' which means unlawful killing, and remember that 'murderousness' describes the quality of being inclined to kill.