The Collaborative International Dictionary of English v.0.48:

Bourn \Bourn\, Bourne \Bourne\, n. [F. borne. See Bound a
   limit.]
   A bound; a boundary; a limit. Hence: Point aimed at; goal.
   [1913 Webster]

         Where the land slopes to its watery bourn. --Cowper.
   [1913 Webster]

         The undiscovered country, from whose bourn
         No traveler returns.                     --Shak.
   [1913 Webster]

         Sole bourn, sole wish, sole object of my song.
                                                  --Wordsworth.
   [1913 Webster]

         To make the doctrine . . . their intellectual bourne.
                                                  --Tyndall.
   [1913 Webster]

The Collaborative International Dictionary of English v.0.48:

Bourn \Bourn\, Bourne \Bourne\, n. [OE. burne, borne, AS. burna;
   akin to OS. brunno spring, G. born, brunnen, OHG. prunno,
   Goth. brunna, Icel. brunnr, and perh. to Gr. ?. The root is
   prob. that of burn, v., because the source of a stream seems
   to issue forth bubbling and boiling from the earth. Cf.
   Torrent, and see Burn, v.]
   A stream or rivulet; a burn.
   [1913 Webster]

         My little boat can safely pass this perilous bourn.
                                                  --Spenser.
   [1913 Webster] Bourn

WordNet (r) 3.0 (2006):

bourn
    n 1: an archaic term for a boundary [syn: bourn, bourne]
    2: an archaic term for a goal or destination [syn: bourn,
       bourne]

Moby Thesaurus II by Grady Ward, 1.0:

98 Moby Thesaurus words for "bourn":
   adolescent stream, anchorage, arroyo, beck, border line, bound,
   boundary, boundary condition, boundary line, braided stream,
   branch, break boundary, breakoff point, brook, brooklet, burn,
   ceiling, channel, circumscription, compass, confine, creek, crick,
   cutoff, cutoff point, deadline, delimitation, destination,
   determinant, division line, end, extremity, finish, floor,
   flowing stream, fluviation, fresh, freshet, frontier, gill, goal,
   harbor, haven, hedge, high-water mark, interface, kill, last stop,
   lazy stream, limen, limit, limitation, limiting factor, line,
   line of demarcation, low-water mark, lower limit, march, mark,
   meandering stream, mete, midchannel, midstream, millstream,
   moving road, navigable river, port, race, racing stream, river,
   rivulet, run, rundle, runlet, runnel, sike, spill stream, start,
   starting line, starting point, stop, stopping place, stream,
   stream action, streamlet, subterranean river, target date, term,
   terminal, terminal date, terminal point, terminus, threshold,
   time allotment, upper limit, wadi, watercourse, waterway