No one knows what bears are "truly" called. And as such, no one knows what "Arctic" really means either.
As the Slovak Studies program at the University of Pittsburgh explains, "bear" is actually just a placeholder name, to protect the speaker from saying something much, much more horrifying:
The Old Slavic people (the linguistic ancestors of today's speakers of, e.g., Slovak, Polish, Croatian), Old Germanic people (the linguistic ancestors of today's speakers of, e.g., English, German, Norwegian), and Old Baltic people (the linguistic ancestors of today's speakers of Latvian and Lithuanian), who lived next to each other and interacted for many generations, came to believe that if you call the bear by his true name, he would hear and understand, and you would fail to catch him, or he would come to harm you. The bear was the only really dangerous animal in their woods. The original word artko was tabooed. Such beliefs about not calling prey and danger by their "true" names are not uncommon among hunters and people in general through the present.
This is a fairly common trope in folklore, particularly stories involving Devils and Magic. Names are typically understood to have power; the act of naming a thing is often believed gives you power over it (see: Rumpelstiltskin). In this case, the act of speaking the true name of The Bear Who Shall Not Be Named would have the opposite effect, by summoning forth That Horrible Creature That We Refer To As "The Brown One" To Avoid Upsetting It By Using Its True Name.
I learned this fact a few years ago, and it continues to entertain me to no end. (Side note, I'm great at parties; remember when people had parties?) But languages evolve over time. And even more recently, I've learned of a new etymological root that ties back to the Bear Who Shall Not Be Named, which becomes infinitely more complicated when you start to consider the self-defined linguistic signifiers.
I'm talking about "Arctic."
As Etymology Online explains:
late 14c., artik, in reference to the north pole of the heavens, from Old French artique and directly from Medieval Latin articus, from Latin arcticus, from Greek arktikos "of the north," literally "of the (constellation) Bear," from arktos "bear; Ursa Major; the region of the north," the Bear being the best-known northern circumpolar constellation.
In other words: "The Arctic" is the place of the bear. By contrast, "Antarctica" is literally the opposite. It's the place of not-bears (or not-the-place of bears, I suppose).
On the surface level, this makes for a rather literal and simplistic naming convention for the planetary poles. The Arctic, the place of the bear, has Polar Bears; Antarctica, the opposite of the place of the bear, does not have polar bears.
That all tracks. Until you remember that "bear" is just a placeholder name for That Big Furry Beast That We're Too Scared To Mention. And so, the Arctic was technically named as the "place of the thing that shall not be named." By extension, the name of Antarctica exists in direct reference to that signifier, which itself is a reference to something that shall not be named—literally, "the opposite of the place of the thing that shall not be named."
What a strange game of linguistic telephone: naming one entire regions after a word used to avoid naming something, then using the same etymological mechanism to name the opposite of that place.