The upshot is that it could be Brythonic for 'Bear' or Gallic for 'stone'...assuming some sort of Anglo-related origin.
In Latin however, there's Arto meaning 'to curtail or compress' and in Greek artios meaning 'fit, proper, perfect'. The truth is, shorter names ending in the -ah sound are almost universal and spring up spontaneously in languages around the world with different meanings. Talk to an African linguist and they'll give you one take on this one whereas English speakers will look to UK occurances, Swedes to Scandinavian, etc. Go around the world collecting meanings for your name and then choose the one that suits....or just ask your parents where they got it from ;o)