▪ I.† bu,n.Obs.rare—1. [perh.ad.ON.búi dweller, *hel-búi hell-dweller: but cf. the interj. boo; also bogle-bo under bogle.] c1300K. Alis. 5956 He..spaak als an helle bu. ▪ II.bu obs. or dial.f. bow n.4, be v., buy. ▪ III.bu Sc. form of boo, v. andint.