The Collaborative International Dictionary of English v.0.48:

Divan \Di*van"\, n. [Per. d[imac]w[=a]n a book of many leaves,
   an account book, a collection of books, a senate, council:
   cf. Ar. daiw[=a]n, F. divan.]
   1. A book; esp., a collection of poems written by one author;
      as, the divan of Hafiz. [Persia]
      [1913 Webster]

   2. In Turkey and other Oriental countries: A council of
      state; a royal court. Also used by the poets for a grand
      deliberative council or assembly. --Pope.
      [1913 Webster]

   3. A chief officer of state. [India]
      [1913 Webster]

   4. A saloon or hall where a council is held, in Oriental
      countries, the state reception room in places, and in the
      houses of the richer citizens. Cushions on the floor or on
      benches are ranged round the room.
      [1913 Webster]

   5. A cushioned seat, or a large, low sofa or couch;
      especially, one fixed to its place, and not movable.
      [1913 Webster]

   6. A coffee and smoking saloon. [Colloq.]
      [1913 Webster]

WordNet (r) 3.0 (2006):

divan
    n 1: a long backless sofa (usually with pillows against a wall)
    2: a Muslim council of state [syn: divan, diwan]
    3: a collection of Persian or Arabic poems (usually by one
       author) [syn: divan, diwan]
    4: a Muslim council chamber or law court [syn: divan, diwan]

Moby Thesaurus II by Grady Ward, 1.0:

42 Moby Thesaurus words for "divan":
   British Cabinet, Sanhedrin, US Cabinet, advisory body,
   advisory council, assembly, association, bench, board,
   body of advisers, borough council, brain trust, cabinet, camarilla,
   chamber, city council, common council, conference, congress,
   consultative assembly, council, council fire, council of ministers,
   council of state, council of war, county council, court,
   deliberative assembly, diet, directory, junta, kitchen cabinet,
   legislature, ministry, parish council, privy council,
   shadow cabinet, soviet, staff, syndicate, synod, tribunal