Most spells in Harry Potter (magic in general) are in Latin. However, at least two spells, namely Stupefy and Obliviate, are in English. Why is that? I found some sources, but they are in general talking about how magical language is Latin.
There are far more languages than (pseudo-)Latin used: scifi.stackexchange.com/questions/82603/…– BCdotWEBAug 16, 2017 at 8:44
1Also, there is no answer to this question. Most close comes this: scifi.stackexchange.com/a/110030/31029– BCdotWEBAug 16, 2017 at 8:46
While those words might be understandable as English, their origins would be in the same languages JKR used for the rest of the spells.– GeoffAtkinsAug 16, 2017 at 11:09
As @BCdotWEB link suggests, there were wizards from many places. Maybe there were old wizards that spoke Anglo-Saxon somewhere.– LeonXAug 16, 2017 at 12:05
It also brings up another question, why does Hogwart's not have Latin classes?– rtaftAug 21, 2017 at 13:27
While RadarUnicorn is correct that spells such as Obliviate and Stupefy ARE pseudo-Latin just like other spells in the HP stories, there is at least one spell that seems to work with an English incantation:
Further reading (from a specialised sci-fi/fantasy site): What Wording Did Witches and Wizards in Other Cultures Use for Spells? and its many duplicates, as well as some of the answers to How could Ron possibly believe that “Sunshine, daisies, butter mellow…” is a real spell?
These spells are, like many other spells in Harry Potter, pseudo Latin.
Obliviate for example comes from the Latin word "oblivia" which means "forgetfulness".
The resemblance to English words is because English, like most European languages, has its roots in Latin.
This is just speculation on my part, but perhaps the language of the spell is representative of the nationality of the person who discovered/created it. I can't recall any mention of the origin of spells in the books.
It is a good theory, although sectumsempra was Snapes invention, and it is Latin. There are multiple instances where characters are discussed experimenting and creating new spells.– rtaftAug 21, 2017 at 13:23