malpractice
n.
1670s, hybrid coined from mal- + practice, n.. Also used in law for "illegal action by which a person seeks a benefit for himself while in a position of trust" (1758).
〔李〕[mal-=bad 不良；practice n.实践，做法→] n. wrong practice in any official or professional position；misconduct 不法行为；玩忽职守；渎职