The word "lunatic" is used to describe someone who acts in a crazy or irrational manner. It implies that the person's behavior is unpredictable or deranged. Full definition
The paperback and e-book versions of Lunatic Fringe are now available for preorder! (talesofthepack.com)
The movie makes them look like lunatics who are bound by jealously and insecurities that these heroes were meant to repel throughout the history of their portrayal in the comic books. (fraghero.com)
Just becuae a bunch of lunatics who call themselves muslims commit crimes in the name of religion, DOES NOT make Islam bad. (religion.blogs.cnn.com)