The Collaborative International Dictionary of English v.0.48:

Shire \Shire\, n. [AS. sc[imac]re, sc[imac]r, a division,
   province, county. Cf. Sheriff.]
   1. A portion of Great Britain originally under the
      supervision of an earl; a territorial division, usually
      identical with a county, but sometimes limited to a
      smaller district; as, Wiltshire, Yorkshire, Richmondshire,
      Hallamshire.
      [1913 Webster]

            An indefinite number of these hundreds make up a
            county or shire.                      --Blackstone.
      [1913 Webster]

   2. A division of a State, embracing several contiguous
      townships; a county. [U. S.]
      [1913 Webster]

   Note: Shire is commonly added to the specific designation of
         a county as a part of its name; as, Yorkshire instead
         of York shire, or the shire of York; Berkshire instead
         of Berks shire. Such expressions as the county of
         Yorkshire, which in a strict sense are tautological,
         are used in England. In the United States the composite
         word is sometimes the only name of a county; as,
         Berkshire county, as it is called in Massachusetts,
         instead of Berks county, as in Pensylvania.
         [1913 Webster]

               The Tyne, Tees, Humber, Wash, Yare, Stour, and
               Thames separate the counties of Northumberland,
               Durham, Yorkshire, Lincolnshire, etc. --Encyc.
                                                  Brit.
         [1913 Webster]

   Knight of the shire. See under Knight.

   Shire clerk, an officer of a county court; also, an under
      sheriff. [Eng.]

   Shire mote (Old. Eng. Law), the county court; sheriff's
      turn, or court. [Obs.] --Cowell. --Blackstone.

   Shire reeve (Old Eng. Law), the reeve, or bailiff, of a
      shire; a sheriff. --Burrill.

   Shire town, the capital town of a county; a county town.

   Shire wick, a county; a shire. [Obs.] --Holland.
      [1913 Webster]

The Collaborative International Dictionary of English v.0.48:

County \Coun"ty\ (koun"t[y^]), n.; pl. Counties (-t[i^]z). [F.
   comt['e], fr. LL. comitatus. See Count.]
   1. An earldom; the domain of a count or earl. [Obs.]
      [1913 Webster]

   2. A circuit or particular portion of a state or kingdom,
      separated from the rest of the territory, for certain
      purposes in the administration of justice and public
      affairs; -- called also a shire. See Shire.
      [1913 Webster]

            Every county, every town, every family, was in
            agitation.                            --Macaulay.
      [1913 Webster]

   3. A count; an earl or lord. [Obs.] --Shak.
      [1913 Webster]

   County commissioners. See Commissioner.

   County corporate, a city or town having the privilege to be
      a county by itself, and to be governed by its own sheriffs
      and other magistrates, irrespective of the officers of the
      county in which it is situated; as London, York, Bristol,
      etc. [Eng.] --Mozley & W.

   County court, a court whose jurisdiction is limited to
      county.

   County palatine, a county distinguished by particular
      privileges; -- so called a palatio (from the palace),
      because the owner had originally royal powers, or the same
      powers, in the administration of justice, as the king had
      in his palace; but these powers are now abridged. The
      counties palatine, in England, are Lancaster, Chester, and
      Durham.

   County rates, rates levied upon the county, and collected
      by the boards of guardians, for the purpose of defraying
      the expenses to which counties are liable, such as
      repairing bridges, jails, etc. [Eng.]

   County seat, a county town. [U.S.]

   County sessions, the general quarter sessions of the peace
      for each county, held four times a year. [Eng.]

   County town, the town of a county, where the county
      business is transacted; a shire town.
      [1913 Webster]

WordNet (r) 3.0 (2006):

shire
    n 1: a former administrative district of England; equivalent to
         a county
    2: British breed of large heavy draft horse [syn: shire,
       shire horse]

Moby Thesaurus II by Grady Ward, 1.0:

45 Moby Thesaurus words for "shire":
   Kreis, archbishopric, archdiocese, arrondissement, bailiwick,
   bishopric, borough, canton, city, commune, congressional district,
   constablewick, county, departement, diocese, district, duchy,
   electoral district, electorate, government, hamlet, hundred,
   magistracy, metropolis, metropolitan area, oblast, okrug, parish,
   precinct, principality, province, region, riding, sheriffalty,
   sheriffwick, shrievalty, soke, stake, state, territory, town,
   township, village, wapentake, ward



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

SHIRE, Eng. law. A district or division of country. Co. Lit. 50 a.