I have learned many things about the cultural origins of specific words in my research for my novel. For instance, the “Colosseum,” as it was originally spelled, got its name from a colossal statue of Nero that stood next to it. So it was almost the Neroseum! But knowing this, I still worried that if I used the word “Coliseum,” readers would think I was referring to the Coliseum in Rome. Could I use the word to mean a coliseum? But what if in the world of my novel there is only one Coliseum? If I capitalize it, because it is the Coliseum of the Golden Empire, will it make readers think I am referring to the Coliseum in Rome? Hopefully the fact that my novel takes place in an entirely different universe will be a tip-off that this is a different Coliseum.

And then there was “barbarians.” This is derived from a word the Greeks used to describe people who didn’t speak Greek. They thought those people sounded like “bar-bar” when they spoke. Or so wikipedia would have us believe. So really, it meant Mediterranean people outside of Greece. And then by the 16th Century several European groups used “Barbaria” to refer to North Africa – AKA The Barbary Coast.
So I ditched “barbarians” and I went with “reivers.” There’s a word you don’t hear every day. Unless you give tours along the English-Scottish border. I uncovered this term while hiking Hadrian’s wall. Or rather, while watching a documentary about the history of the Scottish-English border in preparation for my journey there. Reivers are raiders, from both sides of the border, who stole from their neighbors in the on-going war between England and Scotland. Even when there wasn’t officially a war going on, there was a hostile relationship, and the government of each side encouraged their locals to raid across the border.
Which leads us to platoons, “the smallest military unit commanded by a commissioned officer.” If you want to say “There was a small piece of a big army in town, on duty, with a commanding officer,” you might say “There was a local platoon.” But if you set that “platoon” in a medieval world, you might get a very well read reader who emails you that “This term was first used in the 17th century, not in the Middle Ages, and is anachronistic in this setting.” And then you get to hope most readers don’t know this and won’t be jarred out of the narrative.
If I wanted to write my novel in language that was as authentic as possible to the time and place in which my fictional world is based, then I guess I would have to learn 13th Century Old Prussian and write my novel in that language. Do they have a word for Quinceañera?