Definition of "psycho"

psycho¹

/ˈsaɪ̯.kəʊ̯/

adjective
comparative more psycho, superlative most psycho
1. (colloquial or derogatory) Psychotic or otherwise insane.
  Quotations
  That psycho jawn had snuck a pistol into the gym while we was practicing and started shooting shit up like she was some kinda hot female action hero.
  2006, Noire [pseudonym], Thug-A-Licious: An Urban Erotic Tale, New York, N.Y.: One World/Ballantine Books, page 258
  Oh, she's sweet but a psycho / A little bit psycho / At night she's screamin' / "I'm-ma-ma-ma out my mind"
  2018, Ava Max, Madison Love, Tix, Cook Classics, Cirkut (lyrics and music), “Sweet but Psycho”, in Heaven & Hell‎, performed by Ava Max
noun
plural psychos
1. (derogatory, slang) A person who is psychotic or otherwise insane.
  Quotations
  Oh, she's hot but a psycho / So left but she's right, though / At night she's screamin' / "I'm-ma-ma-ma out my mind"
  2018, Ava Max, Madison Love, Tix, Cook Classics, Cirkut (lyrics and music), “Sweet but Psycho”, in Heaven & Hell‎, performed by Ava Max
2. (derogatory, slang) A person who acts in a bizarre or dangerous manner.

psycho²

/ˈsaɪ̯.kəʊ̯/

noun
uncountable
1. (informal) A class, at a college or university, in which psychology is taught.