The Collaborative International Dictionary of English v.0.48:

Principality \Prin`ci*pal"i*ty\, n.; pl. Principalities. [L.
   principalitas pre["e]minence, excellence: cf. F.
   principalit['e], principaut['e]. See Principal.]
   1. Sovereignty; supreme power; hence, superiority;
      predominance; high, or the highest, station. --Sir P.
      Sidney.
      [1913 Webster]

            Your principalities shall come down, even the crown
            of your glory.                        --Jer. xiii.
                                                  18.
      [1913 Webster]

            The prerogative and principality above everything
            else.                                 --Jer. Taylor.
      [1913 Webster]

   2. A prince; one invested with sovereignty. "Next upstood
      Nisroch, of principalities the prime." --Milton.
      [1913 Webster]

   3. The territory or jurisdiction of a prince; or the country
      which gives title to a prince; as, the principality of
      Wales.
      [1913 Webster]

WordNet (r) 3.0 (2006):

principality
    n 1: territory ruled by a prince [syn: principality,
         princedom]

Moby Thesaurus II by Grady Ward, 1.0:

209 Moby Thesaurus words for "principality":
   Kreis, aedileship, ally, angel, angel of light, angel of love,
   archangel, archbishopric, archdiocese, archduchy, archdukedom,
   archiepiscopacy, archiepiscopate, aristocracy, arrondissement,
   ascendance, ascendancy, bailiwick, balance of power,
   beatified soul, bishopric, body politic, borough, buffer state,
   canonized mortal, canton, captive nation, celestial, chairmanship,
   chancellery, chancellorate, chancellorship, cherub, cherubim,
   chiefery, chiefry, chieftaincy, chieftainry, chieftainship, city,
   city-state, colony, commonweal, commonwealth, commune,
   congressional district, constablewick, consulate, consulship,
   country, county, deanery, departement, dictatorship, dictature,
   diocese, directorship, district, domain, dominance, dominancy,
   domination, dominion, duchy, dukedom, earldom, electoral district,
   electorate, eminent domain, emirate, empery, empire, episcopacy,
   free city, government, governorship, grand duchy, hamlet, headship,
   heavenly being, hegemony, hierarchy, hundred, kingdom, land,
   leadership, lordship, magistracy, magistrateship, magistrature,
   mandant, mandate, mandated territory, mandatee, mandatory, martyr,
   masterdom, mastership, mastery, mayoralty, mayorship,
   messenger of God, metropolis, metropolitan area, metropolitanate,
   metropolitanship, nation, nationality, nobility, oblast, okrug,
   overlordship, papacy, parish, pashadom, pashalic, patriarchate,
   patriarchy, patron saint, polis, polity, pontificality,
   pontificate, popedom, popehood, popeship, possession, power,
   precinct, predominance, predominancy, predomination, preeminence,
   prefectship, prefecture, premiership, preponderance, prepotence,
   prepotency, presidency, presidentship, primacy, prime-ministership,
   prime-ministry, princedom, princeship, principate, proconsulate,
   proconsulship, protectorate, protectorship, province, provostry,
   provostship, puppet government, puppet regime, realm,
   recording angel, rectorate, rectorship, regency, regentship,
   region, republic, riding, ruling class, saint, satellite,
   saved soul, seigniory, seneschalship, seneschalsy, seneschalty,
   seraph, seraphim, settlement, sheikhdom, sheriffalty, sheriffcy,
   sheriffdom, sheriffwick, shire, shrievalty, soke, soul in glory,
   sovereign nation, sovereignty, stake, state, sultanate,
   superiority, superpower, supervisorship, supremacy, suzerainship,
   suzerainty, territory, toparchia, toparchy, town, township,
   tribunate, upper hand, village, vizierate, viziership, wapentake,
   ward, whip hand