The Collaborative International Dictionary of English v.0.48:

Papacy \Pa"pa*cy\, n. [LL. papatia, fr. L. papa a father,
   bishop. See Pope.]
   1. The office and dignity of the pope, or pontiff, of Rome;
      papal jurisdiction.
      [1913 Webster]

   2. The popes, collectively; the succession of popes.
      [1913 Webster]

   3. The Roman Catholic religion; -- commonly used by the
      opponents of the Roman Catholics in disparagement or in an
      opprobrious sense.
      [1913 Webster]

WordNet (r) 3.0 (2006):

papacy
    n 1: the government of the Roman Catholic Church [syn: papacy,
         pontificate]