▪ I.† burdoun1Obs. Common early spelling of bourdon n.1andn.2. ▪ II.† burdoun2Obs. [Cf.OF.bourdon ‘clou à grosse tête?’ (Godef.).] A stud on the boards of a book. c1440Promp. Parv. 56 Burdon of a boke, burdo.1483Cath.Angl. 48 A Burdun of a buke; clauillus.