An insane person is someone who is mentally ill or has a severe mental disorder. This term can be used to describe a variety of different conditions, and there are several words that can be used to refer to an insane person. These include MAD (3 letters), MADMAN (6 letters), MANIAC (6 letters), LOON (4 letters), NUTCASE (7 letters), LUNATIC (7 letters), LOONY (5 letters), and IMBECILE (8 letters). Each of these terms carries its own connotations and implications, but they all refer to someone who is mentally ill or has a severe mental disorder.