Readers, ready your Patronuses; there are some wild curse theories coming your way.
A thread on Reddit, the land of jaw-dropping fan speculation, yielded some suppositions about the Killing Curse, Avada Kedavra, from JK Rowling's "Harry Potter."
Over the years, Potterheads remarked on the phonetic similarities between Avada Kedavra and the age-old trick magician cry "abracadabra!"
The Killing Curse is an outlier in its resemblance to a silly mishmash of expressive sounds -- abracadabra is to party magicians what “Bam!” is to American TV chefs of the 90s -- because most of Rowling's spells derive, quite evidently, from Latin.
Reddit user jodatoufin suggested abracadabra belies a far darker history, sharing,
What I think… is that, in the times before the statute of secrecy, the interactions between muggles and wizards were often violent and deadly. So much so that, even after the idea of wizards faded into mythology, among muggles the killing curse became a thing of folklore. It was the one spell that came away as the 'magic words.' Granted, over time the pronunciation became bastardized from Avada Kedavra to Abra Kadabra, but I think it's one of the few things that stuck among muggle culture since the statute of secrecy.
Tension and mutual fear between Muggles and magical folk are addressed rampantly throughout the series, so it makes sense the one spell to stand the test of time would be the most terrifying and tragic of all.
But wait, there's more! User Canvaverbalist added perhaps Avada Kedavra was initially a healing spell simply taken too far by wizards too powerful.
Because this spell was at first created to cure, what it did in fact was killing the bacteria and viruses in the body, thus healing most illness. But then some clever magician discovered they could expand the spell, make it stronger and even more deadly. That's about when the magicians started to be seen as a treat in general, frowned upon and excluded from society. This is why this word/spell is such a forbidden one, not only because of its direct consequence but also because of all the history it wears.
User aalamb bolstered this theory by reminding readers of Mad-Eye Moody's words to Harry's class when teaching the Unforgivable Curses.
In 'Harry Potter and the Goblet of Fire,' Moody tells Harry's class that they could all attempt to cast the killing curse on him, and as they're untrained students, he'd be unlikely to get as much as a nosebleed. It's possible that this is because without the training and intent, Avada Kedavra would simply cure him of any ailments he might be suffering from. The knowledge that it can be used as a harmless cure is carefully stifled because it invites the possibility of rampant fatal accidents... Therefore, once Avada Kedavra became known as a killing curse, the wizarding authorities and academia had to devise alternate cure spells and a taboo was created on one of the earliest spells.
Sure, everyone could be reading into Rowling's canon too deeply and expanding the history of the wizarding world out of sheer love and nostalgia, but odds are far greater (well, fingers crossed) Jo knows all, and fans barely scratched the surface.