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