Since there is no official word for "collective nouns" how about some of our Latin and Greek scholars trying to outdo each other in coining one? Just to be a good sport, anticipating ridicule, I suggest "sortcohort".

Incidentally, I always thought the collective noun pastime originated in the late seventeen hundreds. But I found a site claiming to have a list of ones current in the fifteenth century.
http://lonestar.texas.net/~rferrell/collects2.html