Usually, when I read a comment that I want to respond to, I just respond to it. But a couple of days ago, a question was posed which I wanted to pontificate about a bit. After all, who doesn't love a good round of pontification? Click down below the break for the question, and my commentary, concerning linguistic conventions in fantasy writing.
First, let's start with the question which got this particular train of thought rolling. From the comments section of my Mini-Reviews Round 13 post:
For most readers, this is a very fuzzy line. What, exactly, is the difference between saying that Applejack wears a Stetson, and saying that she drank a glass of Coca-Cola? In both cases we're dealing with brand names, but (to me at least) the former is non-intrusive while the latter is immersion-breaking. There's a large element of "I know it when I see it" here, but I think there are a few rules of thumb that can be gleaned when it comes to language choice in fantasy (and thus, MLP fanfic). And to find those rules of thumb, I'm going to turn to the most influential linguist/fantasy author who ever put pen to paper.
That's right, it's Tolkien time.
J.R.R. Tolkien's writings concerning Middle-Earth were based on the explicit conceit that they had been translated from the Elvish and Hobbitish languages of the time; Appendix F of Return of the King explains exactly how Tolkien went about "translating" LotR from Westron. It's excellent reading for anyone interested in how to use language as a worldbuilding tool.
The problem with English is, of course, that most of its vocabulary is borrowed from somewhere or other. "Yoga" comes from Sanskrit, as Magrigor notes; is its use appropriate? What about loan words for non-European species, like raccoon or kangaroo? What about words of Norman origin? One could quickly reduce one's usable vocabulary to nothing if one was too zealous in applying the "English origin only" rule to their writing.
Although Middle-Earth is very much Anglo-Saxon in inspiration, Tolkien used words of external origin (Norman, Hebrew, etc.) liberally. Considering his linguistic knowledge, it's safe to say he was well aware of what he was doing. So the question becomes, how do we differentiate between foreign words which have been sufficiently naturalized, and words which still retain a distinctly foreign flavor. Where's the line between the presumably non-immersion-breaking "beef," and words that are more likely to distract a reader by calling attention to word choice?
I think the first answer is to say that words of foreign origin are appropriate, if we assume that those languages have some corollary within the invented world in question. This is a common worldbuilding assumption--I've used Old English as a stand-in for archaic pony writing, for example, and in the stories by NickNack which I just reviewed, he uses German as the griffon language (presumably taking the linguistic origin of "Gilda" as his starting point)--and one that most readers won't object to, if they even recognize it as a worldbuilding assumption. Further, the word ought to represent something which has some place in the fantasy world in question; consider the difference between a pony using the phrase laissez-faire in a fanfic, and one referring to droit du seigneur.
If one wants to retain a strictly regional flavor, though--if one didn't want an unspoken implication that the ponies' language is as full of loan words as our own--more care would be needed. Unfortunately, this comes down mostly to a combination of how "anglicized" a word has become, and how long it's been a part of the English language. These two, in confluence, don't lend themselves to reductive maxims (no "pre-enlightenment is fine!" or the like).
And all this, so far, has excluded the question of brand names. The easy answer is to say that brand names are right out--Coca-Cola, GMC, and all the rest. However, what about stetsons? If Rarity comments that another pony is wearing "shoddy" clothes, is that immersion-breaking? In cases where a brand name is (or has become) accepted as generic, there seems to me to be a lot of grey area. I know that I'd find "Stetson" perfectly acceptable, but would balk at "Kleenex," and I can't come up with any logically consistent reason for that preference.
So, to the question of "yoga," specifically: I personally don't find it jarring, because 1) the concept jives nicely with the setting, 2) there's not a more recognizably "English" word for the same thing, 3) there's no reason to believe that there can't be a race or nation in the world of Equestria which uses a language which could be translated as Sanskrit in the same way that the show ponies' language is translated as English, and 4) it's not a brand name. That may seem like a cumbersome way to go about determining if a word is appropriate or not, but in the end, I think this question has to come down mostly to personal preference and judicious application of the smell test.