bond: English has two distinct words bond, which started life very differently but have gradually grown together. Bond ‘something that binds’  was originally the same word as band (from Old Norse band), and only gradually diverged from it in pronunciation, spelling, and meaning. The key modern legal and financial senses began to develop in the 16th century, the underlying notion being of something one is ‘bound’ or ‘tied’ to by a promise. Bond ‘bound in slavery’ , as in bondservant, is an adjectival use of the late Old English noun bonda ‘householder’, which came from Old Norse bóndi (the second element of húsbóndi, from which English gets husband).
This represented an earlier bóandi, which was originally the present participle of east Norse bóa ‘dwell’, a derivative of the Germanic base *bū- ‘dwell’, (from which English also gets be, boor, booth, bower, build, burly, byelaw, and byre). The semantic association of ‘tying up’ and ‘servitude’ has led to the merging of the two words, as shown in the derivative bondage. => band; be, boor, booth, build, byelaw, neighbour
early 13c., "anything that binds," phonetic variant of band (n.1). For vowel change, see long (adj.); also influenced by Old English bonda "householder," literally "dweller" (see bondage). Legalistic sense first recorded 1590s.