演变路径（由近及远）
词源说明
Contrary to popular belief, not derived from the ancient Mesopotamian city of Ur being one of the first cities.
From German ur-, from Middle High German ur-, from Old High German ur- (“out; without”), from Proto-West Germanic *uʀ-, from Proto-Germanic *uz- (“out”), from Proto-Indo-European *uds- (“up, out”), from Proto-Indo-European *úd (“upwards, away, out, outwards”). Doublet of a- and or-, which is no longer productive (fossilized in e.g. ordeal). Cognate also with Dutch oer- and Dutch oor-.