mal.fea.sance mAl5fi:7z[nts n law (an example of) dishonest and illegal behaviour, esp. by a person in authority （公职人员）违法乱纪行为 Several cases of malpractice and malfeasance in the financial world are currently being investigated. [U] 金融界的几起渎职违规行为正在调查之中。