Definition of "unbound"

unbound

/ʌnˈbaʊnd/

verb
1. simple past and past participle of unbind
adjective
not comparable
1. Not bound; not tied up.
2. Without a binding.
  Quotations
  Beneath an old ebony table were two long carved oak chests. I lifted the lid of one, and at the top was a once-white surplice covered with dust, and beneath was a mass of tracts — Commonwealth Quartos, unbound — a prey to worms and decay.
  1880, William Blades, The Enemies of Books, page 40
3. (nuclear physics, of an atomic nucleus) Lying beyond the proton or neutron drip line; having a negative particle separation energy; capable of decaying by the spontaneous exothermic emission of one or more nucleons.