psycho (adj.)youdaoicibaDictYouDict[psycho 词源字典]
1927, shortening of psychological; 1936 (Raymond Chandler) as shortening of psychopathic (adj.).[psycho etymology, psycho origin, 英语词源]
psycho (n.)youdaoicibaDictYouDict
1925, short for psychologist; as short for psychopath from 1942.