The Collaborative International Dictionary of English v.0.48:

Boundary \Bound"a*ry\, n.; pl. Boundaries [From Bound a
   limit; cf. LL. bonnarium piece of land with fixed limits.]
   That which indicates or fixes a limit or extent, or marks a
   bound, as of a territory; a bounding or separating line; a
   real or imaginary limit.
   [1913 Webster]

         But still his native country lies
         Beyond the boundaries of the skies.      --N. Cotton.
   [1913 Webster]

         That bright and tranquil stream, the boundary of Louth
         and Meath.                               --Macaulay.
   [1913 Webster]

         Sensation and reflection are the boundaries of our
         thoughts.                                --Locke.
   [1913 Webster]

   Syn: Limit; bound; border; term; termination; barrier; verge;
        confines; precinct.

   Usage: Bound, Boundary. Boundary, in its original and
          strictest sense, is a visible object or mark
          indicating a limit. Bound is the limit itself. But in
          ordinary usage the two words are made interchangeable.
          [1913 Webster]

WordNet (r) 3.0 (2006):

boundary
    n 1: the line or plane indicating the limit or extent of
         something [syn: boundary, bound, bounds]
    2: a line determining the limits of an area [syn: boundary,
       edge, bound]
    3: the greatest possible degree of something; "what he did was
       beyond the bounds of acceptable behavior"; "to the limit of
       his ability" [syn: limit, bound, boundary]

Moby Thesaurus II by Grady Ward, 1.0:

171 Moby Thesaurus words for "boundary":
   Thule, Ultima Thule, ankle, articulation, balustrade, barrier,
   bisector, bitter end, border line, bordering, borderline, borders,
   bottom dollar, bound, boundary condition, boundary line, bounding,
   bounds, bourn, break boundary, breakoff point, butt, butt end,
   caesura, caudal, ceiling, cervix, circumscription, clinch, closure,
   coastal, colon, comma, compass, conclusive, confine, confinement,
   confines, connecting link, connecting rod, connection, continence,
   coupling, cutoff, cutoff point, deadline, definitive, delimitation,
   determinant, determinative, determining, diameter, discipline,
   divider, division line, dovetail, elbow, embrace, end, endmost,
   equator, eventual, extreme, extremity, fag end, farthest,
   farthest bound, fence, final, finish, floor, fringing, frontier,
   frontiers, gliding joint, halfway mark, hedge, high-water mark,
   hinge, hinged joint, hip, interface, join, joining, joint,
   jumping-off place, juncture, knee, knuckle, last, limbic, limen,
   liminal, limit, limitation, limiting, limiting factor, limits,
   line, line of demarcation, link, littoral, low-water mark,
   lower limit, march, marginal, mark, mete, miter, moderation,
   mortise, neck, nib, partition, pause, perimeter, period, pivot,
   pivot joint, point, polar, pole, precincts, prescription,
   proscription, purlieus, qualification, rabbet, rail, railing,
   restrain, restriction, rimming, scarf, seam, semicolon, shoulder,
   skirting, start, starting line, starting point, stitch, stone wall,
   stop, stub, stump, suture, symphysis, tag, tag end, tail, tail end,
   target date, term, terminal, terminal date, terminating,
   terminative, terminus, threshold, tie rod, time allotment, tip,
   toggle, toggle joint, ultimate, union, upper limit, wall, weld,
   wrist



Bouvier's Law Dictionary, Revised 6th Ed (1856):

BOUNDARY, estates. By this term is understood in general, every separation,
natural or artificial, which marks the confines or line of division of two
contiguous estates. 3 Toull. n. 171.
     2. Boundary also signifies stones or other materials inserted in the
earth on the confines of two estates.
     3. Boundaries are either natural or artificial. A river or other stream
is a natural boundary, and in that case the centre of the stream is the
line. 20 John. R. 91; 12 John. R. 252; 1 Rand. R. 417; 1 Halst. R. 1; 2 N.
H. Rep. 369; 6 Cowen, R. 579; 4 Pick. 268; 3 Randolph's R. 33 4 Mason's R.
349-397.
     4. An artificial boundary is one made by man.
     5. The description of land, in a deed, by specific boundaries, is
conclusive as to the quantity; and if the quantity be expressed as a part of
the description, it will be inoperative, and it is immaterial whether the
quantity contained within the specific boundaries, be greater or less than
that expressed; 5 Mass. 357; 1 Caines' R. 493; 2 John. R. 27; 15 John. 471;
17 John. R. 146; Id. 29; 6 Cranch, 237; 4 Hen. & Munf. 125; 2 Bay, R. 515;
and the same rule is applicable, although neither the courses and distances,
nor the estimated contents, correspond with such specific boundaries; 6
Mass. 131; 11 Mass. 193; 2 Mass. 380; 5 Mass. 497; but these rules do not
apply in cases where adherence to them would be plainly absurd. 17 Mass.
207. Vide 17 S. & R. 104; 2 Mer. R. 507; 1 Swanst. 9; 4 Ves. 180; 1 Stark.
Ev. 169; 1 Phil. Ev. Index, h. t.; Chit. Pr. Index, h. t.; 1 Supp. to Ves.
jr. 276; 2 Hill. Ab. c. 24, Sec. 209, and Index, h. t.
     6. When a boundary, fixed and by mutual consent, has been permitted to
stand for twenty-one years, it cannot afterwards be disturbed. In accordance
with this rule, it has been decided, that where town lots have been occupied
up to a line fence between them, for more than twenty-one years, each party
gained an incontrovertible right to the line thus established, and this
whether either party knew of the adverse claim or not; and whether either
party has more or less ground than was originally in the lot he owns. 9
Watts, R. 565. See Hov. Fr. c. 8, p. 239 to 243; 3 Sum. R 170 Poth. Contr.
de Societe, prem. app. n. 231.
     7. Boundaries are frequently marked by partition fences, ditches,
hedges, trees, &c. When such a fence is built by one of the owners of the
land, on his own premises, it belongs to him exclusively; when built by both
at joint expense, each is the owner of that part on his own land. 5 Taunt.
20. When the boundary is a hedge and a single ditch, it is presumed to
belong to him on whose side the hedge is, because he who dug the ditch is
presumed to have thrown the earth upon his own land, which was alone lawful
to do, and that the hedge was planted, as is usual, on the top of the bank
thus raised. 3 Taunt. 138. But if there is a ditch on each side of the
hedge, or no ditch at all, the hedge is presumed to be the common property
of both proprietors. Arch. N. P. 328; 2 Greenl. Ev. Sec. 617. A tree growing
in the boundary line is the joint property of both owners of the land. 12 N.
H. Rep. 454.
     8. Disputes arising from a confusion of boundaries may be generally
settled by an action at law. But courts of equity will entertain a bill for
the settlement of boundaries, when the rights of one of the parties may be
established upon equitable grounds. 4 Bouv. Inst. n. 3923.



The Devil's Dictionary (1881-1906):

BOUNDARY, n.  In political geography, an imaginary line between two
nations, separating the imaginary rights of one from the imaginary
rights of the other.


U.S. Gazetteer Counties (2000):

Boundary -- U.S. County in Idaho
   Population (2000):    9871
   Housing Units (2000): 4095
   Land area (2000):     1268.806171 sq. miles (3286.192758 sq. km)
   Water area (2000):    9.401069 sq. miles (24.348657 sq. km)
   Total area (2000):    1278.207240 sq. miles (3310.541415 sq. km)
   Located within:       Idaho (ID), FIPS 16
   Location:             48.758435 N, 116.373036 W
   Headwords:
    Boundary
    Boundary, ID
    Boundary County
    Boundary County, ID