A colloquium can be an informal conference as well as an academic seminar of scholars or experts. One example might be a scientific colloquium on dark biology. Traditionally colloquiums are led by a different lecturer and on a different topic at each meeting.
Beginning around 1459 Latin took the word from colloquy, which still means "a conversation." Colloquium itself was borrowed from Latin in 1609, com- meaning "together" and loqui meaning "speak." Colloquium originally implied a "conference, conversation," the earliest known record is in the Douay Bible from 1609. Small colloquiums were attended to discuss Reformation as well as Protestantism during religious upheavals of the 14th century. For example in 1595 the Colloquium Marianum was established in Ingolstadt, Baveria, by a Jesuit priest named Father Jakob Rem.
At the time Maximilian II, empathize greatly with Protestantism. As a result, throughout his reign a major apostasy from the catholic faith arose with the exception of Bavaria. Duke Albrecht of Bavaria, penned a letter to a close friend, Cardinal Morone saying, "It is clear; the tricks of the opponents have no other intention than to destroy everything which is left of the catholic faith in Germany."
The Council of Trent had given explicit instructions for the Catholic Reformation, but the forces to carry on such an endeavor were inadequate. The famous Colloquium Marianum was founded on May 4, 1595 by Father Rem as an elite society which included the greater part of all future spiritual and intellectual leaders of the Counter Reformation. Eventually it became a religious Marian center of high standards and at the same time played a primary role within European history. In view of the individuals that were educated and nurtured in that enviromnet there is little doubt that the good Father deserves credit for the affect of the Marian Colloquium as it spread across Europe.
By 1751 colloquium was in common usage in the English language and between 1797 and 1809 theTomlins Law Dictionary began to define its use in law as, “ Colloquium, a colloquendo. A talking together, or affirming of a thing, laid in declarations for words in actions of slander, etc.” Many of today’s academic departments often have a weekly or bi-weekly colloquium, which differs from other seminars in that it is generally aimed at the whole department or even the university as a whole rather than an audience of specialists. Thus, it is a wider conversation among the whole department or school. *
Plural forms can be colloquiums or colloquia and some useful synonyms to describe meetings for the exchange of views are conference, discussion, parley, and seminar. One might call it a powwow to describe a casual conversation and as for slang, a modern substitute could be called a rap session.
Sources:
* Tip ‘O The Hat to unperson for the information about today’s academic colloquia!
400 Years Mother Thrice Admirable:
www.udayton.edu/mary/resources/ motherthriceadmirable.htm
bartleby.com:
http://www.bartleby.com/cgi-bin/texis/webinator/sitesearch?FILTER=&query=colloquium&x=0&y=0
colloquium:
http://dictionary.oed.com.ezproxy.library.arizona.edu/cgi/entry/50044142
Online Etymology:
http://www.etymonline.com/index.php?search=colloquium&searchmode=none