The Collaborative International Dictionary of English v.0.48:

Symposium \Sym*po"si*um\, n.; pl. Symposia. [L., fr. Gr.
   sympo`sion a drinking party, feast; sy`n with + po`sis a
   drinking. See Syn-, and cf. Potable.]
   1. A drinking together; a merry feast. --T. Warton.
      [1913 Webster]

   2. A collection of short essays by different authors on a
      common topic; -- so called from the appellation given to
      the philosophical dialogue by the Greeks.
      [1913 Webster]

WordNet (r) 3.0 (2006):

symposium
    n 1: a meeting or conference for the public discussion of some
         topic especially one in which the participants form an
         audience and make presentations