An entity a is an object aggregate if and only if there is a mutually exhaustive and pairwise disjoint partition of a into objects
Editor note:
BFO 2 Reference: object aggregates may gain and lose parts while remaining numerically identical (one and the same individual) over time. This holds both for aggregates whose membership is determined naturally (the aggregate of cells in your body) and aggregates determined by fiat (a baseball team, a congressional committee).