acervation

acervation

(ˌæsəˈveɪʃən)
n
formal a heaping or piling up, gathering, accumulation
Collins English Dictionary – Complete and Unabridged, 12th Edition 2014 © HarperCollins Publishers 1991, 1994, 1998, 2000, 2003, 2006, 2007, 2009, 2011, 2014

Acervation

 a heaping up; an accumulation, especially in the form of a tight cluster—Wilkes.
Dictionary of Collective Nouns and Group Terms. Copyright 2008 The Gale Group, Inc. All rights reserved.