Where does “oor-” come from?

oor- (Middle Dutch) comes from Old Dutch ur-, from Proto-West Germanic uʀ-, from Proto-Germanic uz-, from Proto-Indo-European uss-, from Proto-Indo-European uds-, from Proto-Indo-European úd — out, outward.

Ancestry of “oor-”, step by step

StepLanguageWordMeaning
1Old Dutchur-—
2Proto-West Germanicuʀ-out, over; off, away
3Proto-Germanicuz-up, out
4Proto-Indo-Europeanuss-—
5Proto-Indo-Europeanuds-up, out
6Proto-Indo-Europeanúdout, outward
Every word from Proto-Indo-European úd →Every word from Proto-Indo-European uds- →Every word from Proto-Indo-European uss- →