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In HP, do Wizards from different nationalities have different names for spells, and if so do they have to pronounce them as such during the casting?
It seems that more veteran wizards don't seem to need to pronounce many of the spells they are casting, and whilst I am sure this has been explained somewhere, I imagine it has something to do with loading the spell with meaning/empowerment.
However, younger wizards DO seem to need to say the words of the spell they are casting, and if so how is this affected by different languages? Would a mute non-muggle be unable to qualify for wizardry, for example?