Source : Webster's Revised Unabridged Dictionary (1913)

Concretion \Con*cre"tion\, n. [L. concretio.]
   1. The process of concreting; the process of uniting or of
      becoming united, as particles of matter into a mass;
      solidification.

Source : WordNet®

concretion
     n 1: the formation of stonelike objects within a body organ
          (e.g., the kidneys)
     2: a hard lump produced by the concretion of mineral salts;
        found in hollow organs or ducts of the body; "renal
        calculi can be very painful" [syn: {calculus}]
     3: an increase in the density of something [syn: {compaction},
        {compression}, {densification}]
     4: the union of diverse things into one body or form or group;
        the growing together of parts [syn: {coalescence}, {coalescency},
         {coalition}, {conglutination}]