The Collaborative International Dictionary of English v.0.48:

Prefecture \Pre"fec*ture\ (?; 277), n. [L. praefectura: cf. F.
   pr['e]fecture.]
   The office, position, or jurisdiction of a prefect; also, his
   official residence.
   [1913 Webster]

WordNet (r) 3.0 (2006):

prefecture
    n 1: the district administered by a prefect (as in France or
         Japan or the Roman Empire)
    2: the office of prefect

Moby Thesaurus II by Grady Ward, 1.0:

84 Moby Thesaurus words for "prefecture":
   aedileship, archbishopric, archiepiscopacy, archiepiscopate,
   aristocracy, bishopric, chairmanship, chancellery, chancellorate,
   chancellorship, chiefery, chiefry, chieftaincy, chieftainry,
   chieftainship, consulate, consulship, deanery, dictatorship,
   dictature, directorship, emirate, episcopacy, governorship,
   headship, hegemony, hierarchy, leadership, lordship, magistracy,
   magistrateship, magistrature, masterdom, mastership, mastery,
   mayoralty, mayorship, metropolitanate, metropolitanship, nobility,
   papacy, pashadom, pashalic, patriarchate, patriarchy,
   pontificality, pontificate, popedom, popehood, popeship,
   prefectship, premiership, presidency, presidentship,
   prime-ministership, prime-ministry, princedom, princeship,
   principality, proconsulate, proconsulship, protectorate,
   protectorship, provostry, provostship, rectorate, rectorship,
   regency, regentship, ruling class, seigniory, seneschalship,
   seneschalsy, sheikhdom, sheriffalty, sheriffcy, sheriffdom,
   shrievalty, supervisorship, suzerainship, suzerainty, tribunate,
   vizierate, viziership