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.

2. A mass or nodule of solid matter formed by growing together, by congelation, condensation, coagulation, induration, etc.; a clot; a lump; a calculus.

Accidental ossifications or deposits of phosphates of lime in certain organs . . . are called osseous concretions.
Dunglison.

3. (Geol.) A rounded mass or nodule produced by an aggregation of the material around a center; as, the calcareous concretions common in beds of clay.