Sorry, bit of a Harry Potter joke for the title, but it's applicable for this post. Almost all Rowling geeks could tell you that the first name of Draco Malfoy (the archenemisis of Harry in school) comes from the Latin word for "dragon". However, where does Malfoy derive from? First, the prefix -mal. This is recognizable even in English as meaning "bad" (as in maleficent, malicious, or malignant). It is then unsurprising that mal was a word in French which meant "evil". This is from Latin malus, also "evil", from Proto-Indo-European mel, "wrong", through Proto-Italic. Here it gets fascinating: the foy part of Malfoy meant "trust" as foi in Old French. This is an alteration of Latin fides, "faith", which ultimately stems (somehow) from the Proto-Indo-European bheidh, which meant "to trust". Since Malfoy was a bad character who later became good, and his name incorporates both bad and good components, this means that J.K. Rowling not only planned his future from the beginning, but that she was also a whimsical etymologist!
Adam Aleksic has been described as the internet's sixth most famous etymologist. He loves writing about himself in the third person, he's a freshman at Harvard University, and he has disturbing interests in linguistics, vexillology, geography, board games, limericks, and law.
The Etymology Nerd