The Collaborative International Dictionary of English v.0.48:

Symposiac \Sym*po"si*ac\, a. [L. symposiacus, Gr. ?.]
   Of or pertaining to compotations and merrymaking; happening
   where company is drinking together; as, symposiac meetings.
   [1913 Webster]

         Symposiac disputations amongst my acquaintance.
                                                  --Arbuthnot.
   [1913 Webster]

The Collaborative International Dictionary of English v.0.48:

Symposiac \Sym*po"si*ac\, n.
   A conference or conversation of philosophers at a banquet;
   hence, any similar gathering.
   [1913 Webster]