Maniac
Part of speech: noun
Definition: An insane person, especially one who suffers from a mania. A fanatic, a person with an obsession.
Example sentence: Our society is run by insane people for insane objectives. I think we're being run by maniacs for maniacal ends and I think I'm liable to be put away as insane for expressing that. That's what's insane about it.
Lunatic
Part of speech: noun
Definition: An insane person.
Part of speech: adjective
Definition: crazed, mad, insane, demented
Example sentence: I'm a crazy lunatic, but a lot of the time I'm just sitting at home watching movies.