Ur-
The prefix Ur is added to a word to denote the original, primeval or source version of what that root word refers to. When used in German it can mean extremely; original, primeval, earliest, belonging to the first stages of history; or great- in the sense of great-grandmother. An Urwald is a primeval forest, and an Urmensch is a primeval human.
Used in English ur- indicates the original or beginning version of something, for example an ur-language that is the origin of all later languages. There are also references to an Ur-Hamlet play which might have been an early source or inspiration for the playwright William Shakespeare.
Interestingly perhaps the best known use of the Ur- prefix is in the English version of the Italian title of Umberto Eco’s much referenced essay, Il fascismo eterno – Ur-Fascismo, variously translated as Ur-Fascism or else: Eternal Fascism: Fourteen Ways of Looking at a Blackshirt.