WordNet (r) 3.0 (2006):

colloquium
    n 1: an academic meeting or seminar usually led by a different
         lecturer and on a different topic at each meeting
    2: an address to an academic meeting or seminar

Moby Thesaurus II by Grady Ward, 1.0:

79 Moby Thesaurus words for "colloquium":
   airing, analysis, assemblee, assembly, assignation, at home, ball,
   brawl, buzz session, canvassing, caucus, colloquy, commission,
   committee, conclave, concourse, conference, congregation, congress,
   consideration, conventicle, convention, convocation, council,
   dance, date, debate, debating, deliberation, dialectic, dialogue,
   diet, discussion, eisteddfod, examination, exchange of views,
   festivity, fete, forgathering, forum, gathering, get-together,
   housewarming, investigation, joint discussion, levee,
   logical analysis, logical discussion, meet, meeting,
   open discussion, open forum, palaver, panel, panel discussion,
   party, plenum, prom, quorum, rally, rap, rap session, reception,
   rendezvous, review, seance, seminar, session, shindig, sit-in,
   sitting, soiree, study, symposium, synod, town meeting, treatment,
   turnout, ventilation