aggĕrātĭo — Lewis & Short
aggĕrātĭo (adg-), ōnis, f.1. aggero,
I a heaping up; in concr., that which is heaped up, a mole, dike (not before the Aug. per.):
naves supra adgerationem, quae fuerat sub aquā, sederunt,Vitr. 10, 22, 263; Just. 2, 1 fin.