The most prevalent and widely held misconception about or wrong definition of this word is "psychotic" meaning "murderous" or "deranged and/or violent". The actual word as used by psychiatrists or anyone who knows much about mental illness does not carry any connotation of "dangerous" or "violent". This misuse of the word is seen in expressions like "psychotic killer" or something like "I might go psychotic and kill people" or similar instances. As slink says, the correct meaning of the word is free from any suggestion of evil or violence, and simply refers to disordered thought, which demonstrably does not carry any inreased likelihood of violence or evil in the sufferer. This is a very widespread misapprehension and is reinforced by trash media and films generally. I'm also psychotic sometimes but am not a sociopath.