Malfeasance implies some sort of misbehavior, and the etymology does as well. It arose from the Old French word malfaisance, from the verb malfaire, meaning "to do evil". This originated from Latin malefacere, which is composed of the words male, meaning "evil", and facere, meaning "to do" or "make". Male can be conjugated to malus, which, through Proto-Italic, most likely derives from the Proto-Indo-European reconstruction mel, which meant "to deceive". Now, you may have noticed that the words maleficent and malefactor are similar in construction and definition. Indeed, maleficent (through Latin maleficus, meaning "criminal") also traces back to the words male and ficus, and malefactor comes straight from malefacere. Although the word malfeasance was first borrowed into English in the 1690s. it wasn't used so commonly until the 1800s, and since then, usage has increased more than tenfold.
Adam Aleksic, a freshman studying linguistics at Harvard University, has been described as the internet's sixth most famous etymologist. He has disturbing interests in words, vexillology, geography, board games, limericks, and law, and he loves writing about himself in the third person.
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