misfeasance (n.) Look up misfeasance at Dictionary.com
"wrongful exercise of lawful authority or improper performance of a lawful act," 1590s, from Middle French mesfaisance, from mesfaisant, present participle of Old French mesfaire "to misdo," from mes- "wrongly" (see mis- (2)) + faire "to do," from Latin facere "to perform" (see factitious).