This day in geek history: September 1
1984
1984 Masquerade entry: The Lords of Darkness (from stories by Tanith Lee) made & worn by a group UCLA students
Masquerade at which the term "cosplay" is coined: A Japanese reporter attended the 1984 WorldCon and later wrote a description of the costume phenomenon he was observing, especially the Masquerade. He used two foreign loan words ("costume" and "play") which he smashed together into the portmanteau "cosplay".
http://www.strangelandcostumes.com/history.html
http://www.wsfs.org/bm/minutes-1984.html
http://www.fanac.org/worldcon/LA_Con/w84-p00.html