I. “+ adjective
Etymology: Middle English unbounden, from Old English unbunden, from un- (I) + bunden bound, past participle of bindan to bind — more at bind
: not bound: as
a.
(1) : unfastened
(2) : unconfined
b. : not having the leaves fastened or sewn together
an unbound book
c. : not held in chemical or physical combination
II. adjective
Etymology: probably from un- (I) + (assumed) obsolete English bound, past participle of English bound (to set limits to)
obsolete : unbounded