An Etymological Dictionary of the German Language/Annotated/um

by Friedrich Kluge

um, adverb and preposition ‘about, around,’ from the equivalent Middle High German umbe (ümbe), Old High German umbi, cannot be regarded as directly corresponding to Greek ἀμφί, Sanscrit abhi, ‘about,’ for then the Old High German form would be umb. Old High German unbi is rather a compound of this *umb, with the preposition bī̆, ‘by’; so too Old Saxon umbi, Anglo-Saxon ymbe (but ymb directly corresponds to Sanscrit abhi). —