Concretion

Part of speech: noun (n.)

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