A crowded mass of independent but similar units; a cluster. SYN: agglomeration.
- familial a. occurrence of a trait in more members of a family than can be readily accounted for by chance; presumptive but not cogent evidence of the operation of genetic factors.
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ag·gre·ga·tion (ag″rə-gaґshən) 1. massing of materials together as in clumping. 2. a clumped mass of material.Medical dictionary. 2011.