An Etymological Dictionary of the German Language/Annotated/bei
bei, preposition and adverb, ‘by, near, about’; the accented form of the unaccented prefix be; the Goth used in both cases bĭ; the Englishman makes a distinction like the German; Anglo-Saxon bî, English by, but be as a prefix. Old High German bî and bi- (compare also Beichte, Beispiel). In Gothic bĭ means ‘around, near’; hence its kinship with Greek ἀμφί, Latin ambi- is probable; the loss of the first syllable am- also occurs in the Old Teutonic word for beide; the base is probably ambhi-; compare also um.