multifandom

Etymology
From

Adjective

 * 1) Involving or participating in more than one fandom.
 * 2) * 2003, Afterword Q&A, in Gemma Files, Kissing Carrion, Prime Books (2003), ISBN 9781894815635, page 222:
 * I was at Ad Astra, Toronto's biggest yearly multifandom geek romp, when I got the initial idea