An Etymological Dictionary of the German Language/Annotated/Bai

Bai (1.), feminine, ‘bay of a window,’ from Middle High German beie, ‘window,’ which with the following word is of Romance origin; compare English bay, French baie, ‘bay (of a window).’

Bai (2.), feminine, ‘bay,’ derived through Low German from English bay (Middle English baie), which was borrowed from Romance; French baie, Italian baja, Spanish and Iber. (in Isidore), baja, ‘haven’; properly identical with the preceding word.