Agriarctos is a word that represents a prehistoric bear. However, if you want to use different synonyms for this word, there are plenty of options. Some synonyms that you can use for Agriarctos are brown bear, black bear, polar bear, grizzly bear, and Asiatic black bear. These synonyms represent different species of bears, which are differentiated based on their habitat and physical characteristics. Brown bears are commonly found in North America, while black bears are found throughout the continent. On the other hand, polar bears are found in the Arctic region, and grizzly bears are found in the Western United States and Canada. Asiatic black bears are predominantly found in Asia. These synonyms allow you to vary the language and make it more engaging.