psycho
n. countablen. someone who behaves in a very strange, scary, or violent way. It is a very rude word, so be careful when you use it.
n. a person who is perceived as mentally unstable, aggressive, or dangerously unpredictable. Highly informal and often considered offensive or stigmatising in clinical contexts.
He started acting like a total psycho during the argument.
The neighbors thought he was a psycho because he would scream at his lawn in the middle of the night.
While the film portrays the antagonist as a typical Hollywood psycho, modern critics argue the characterization relies on outdated and harmful tropes regarding mental health.
Clipping of psychotic or psychopath + -o (“person with characteristic”). Compare sicko.
Clipping of psychology.
Informal and derogatory; typically used as a predicative noun or a modifier in casual speech.