köken: From Middle High German vride, from Old High German fridu. See also Dutch vrede, Danish fred, Swedish fred, English frith (“peace”). Starting in the 18th century, the weak form Friede started shifting to strong Frieden through spread of the ending from the oblique forms.
köken: Inherited from Proto-Slavic *mirъ (“peace; world”), from Proto-Balto-Slavic *meiˀrás (“peace”), from Proto-Indo-European *mey(H)-ró-s. The dual meaning of "peace" and "world" is unique to Slavic. The pre-1918 orthography had an orthographical distinction of the two identically pronounced words to avoid confusion.