There are some readers who are not fans of the spells created by J.K. Rowling to flesh out the Potterverse. Her loose plying of Latin into incantations throughout the series irks certain diehard linguistic buffs.
But there’s a lot more to Rowling’s spell system than meets the eye.
In the essay collection Harry Potter and History, there is an essay titled “Severus Snape and the Standard Book of Spells: Ancient Tongues in the Wizarding World” by M. G. DuPree that points out something you might have missed between your swishes and flicks:
There’s a linguist’s saying about English speakers that we go to work in Latin and come home in Anglo-Saxon. Meaning that much of our professional language (words like office, supervisor, colleague — even computer and telephone) comes from the Latin-derived French. While the language of home (house, hearth, fire) comes to us from the German-derived Anglo-Saxon. To use Latin is to ally yourself with all of these powerful connotations at once: mystery, power, and formalism. Thus, it is interesting to note that the wizarding world falls into the same patterns of speech, with many lower-level hexes and household charms in English, such as Scourgify. It’s in the higher-order spells that one sees the shift to Latin and Latinate phrases: Expecto Patronum, Cave Inimicum, Fidelius, Expelliarmus, Finite Incantatem.
Rarest of all spell languages in the British wizarding world is Greek, which makes surprisingly few appearances. In pure form, there are only two Greek-based spells mentioned in all of the seven books: Anapeo and Episkey. The interesting thing to note is that both of these are spells with medical uses, which should not be surprising: in the ancient world, Greek was the language of physicians.
It shouldn’t really come as that much of a surprise—Rowling studied classics and linguistics at university—but it’s always impressive to see how careful thought goes into a magical system. For all that the naysayers may dislike how Rowling used Latin in her spell systems, it is clear that she gave the matter a great deal of thought.