Comes from the ancient city of 'Ur' in Mesapotamia. It means 'original'. It started out as a German usage, but it now appears more widely in lots of academic contexts, eg 'Urtext' is a music or literary edition that goes back to the original manuscript or first published edition and strips away all changes and additions made by later editors. 'Ursprache' in German is an original language - typically one lost in time, leaving only common traces in more modern ones - such as the ancient common ancestor of Sanskrit and other Indo-European languages/language families. I would say anyone familar with this would have got the sense 'urwatch' - it's quite a nice coinage I think!