aggregate [ag´rĕgat] individuals, families, or other groupings who are associated because of similar social, personal, health care, or other needs or interests. ag·gre·gate (ag'rĕgāt), 1. To unite or come together in a mass or cluster. 2. The total of individual units making up a mass or cluster. [L. aggrego, pp. atus, to add to, fr. grex ...