The Collaborative International Dictionary of English v.0.48:

Seminar \Sem`i*nar"\, n. [G. See Seminary, n.]
   A group of students engaged, under the guidance of an
   instructor, in original research in a particular line of
   study, and in the exposition of the results by theses,
   lectures, etc.; -- formerly called also seminary, now
   seldom used in this sense.
   [Webster 1913 Suppl. +PJC] Seminarian

WordNet (r) 3.0 (2006):

seminar
    n 1: any meeting for an exchange of ideas
    2: a course offered for a small group of advanced students

Moby Thesaurus II by Grady Ward, 1.0:

58 Moby Thesaurus words for "seminar":
   academic specialty, airing, analysis, area, buzz session,
   canvassing, classical education, colloquium, colloquy, conference,
   consideration, core curriculum, course, course of study,
   curriculum, debate, debating, deliberation, dialectic, dialogue,
   discipline, discussion, elective, examination, exchange of views,
   field, forum, general education, general studies, humanities,
   investigation, joint discussion, liberal arts, logical analysis,
   logical discussion, major, minor, open discussion, open forum,
   palaver, panel discussion, proseminar, quadrivium, rap,
   rap session, refresher course, review, scientific education,
   specialty, study, subdiscipline, subject, symposium,
   technical education, town meeting, treatment, trivium,
   ventilation