An Etymological Dictionary of the German Language/Annotated/brach

by Friedrich Kluge

brach, adjective (especially in compounds such as Brachfeld, &c.), ‘uncultivated, fallow,’ merely Modern High German. In Middle High German there is only the compound brâchkmânôt, ‘June,’ which contains a substantive brâche, feminine, Old High German brâhha (Middle Low German brâke), ‘aratio prima,’ as its first component; Brache is ‘turning up the soil after harvest’; from brechen.