concretion n the formation of stonelike objects within a body organ (e.g., the kidneys) n a hard lump produced by the concretion of mineral salts; found in hollow organs or ducts of the body n an increase in the density of something n the union of diverse things into one body or form or group; the growing together of parts Synonym(s) calculus compaction compression densification coalescence coalescency coalition conglutination