Technically a "polar bear" would make more etymological sense if it was an "arctic bear". The word bear, meaning "a big carnivorous animal", comes from the Middle English term bere, from the Old English term bera, from the Proto-Germanic term bero. All of these end-vowel-switching words meant "bear", but their etymon, the Proto-Indo-European root bher, meant "brown", which proves that brown bears are also etymologically correct. But wait! People 8,000 years ago must have encountered bears too; why doesn't the current name stem from the PIE word for "bear" (which was hrtkos)? Well, the term mostly died out, to be replaced by this other, metynomic one, but it survived in Ancient Greek and Latin, as arktos and ursus, respectively. This former word was also later borrowed into Latin as arcticus, or "northern", since many bears lived in the north. Finally it went into English as arctic, with the definition we know today. How curious....
Adam Aleksic has been described as the internet's sixth most famous etymologist. He loves writing about himself in the third person, he's a freshman at Harvard University, and he has disturbing interests in linguistics, vexillology, geography, board games, limericks, and law.
The Etymology Nerd