1. the union of diverse things into one body or form or group
the growing together of parts

Synonym: coalescencecoalescencycoalitionconglutination

2. an increase in the density of something

Synonym: compactioncompressiondensification

3. a hard lump produced by the concretion of mineral salts
found in hollow organs or ducts of the body

e.g. renal calculi can be very painful

Synonym: calculus

4. the formation of stonelike objects within a body organ (e.g., the kidneys)