There are a ton of words (like hundreds) for bear in Finnish. A long time ago for the ancient Finns bear was a respected (even worshiped) but also a feared animal. So there exist a lot of euphemisms, which were used instead so as not to summon it by using its proper name. "Oksi" is probably the oldest, most original word (although no longer used), and "otso" is closest to it (and still in use, but uncommon).
Bear is the national animal of Finland, and also known as "metsän kuningas" - "king of the forest".