What does concretion mean?
A concretion is a hard, compact mass — most familiar as a rounded, stony nodule formed naturally within layers of sedimentary rock. As groundwater percolates through sediment, minerals precipitate around a nucleus such as a shell, bone, or grain of sand, cementing particles together into a body often noticeably harder than the surrounding rock. When erosion strips away the softer matrix, these durable masses are left exposed on the surface. The word also names the underlying process of particles growing or fusing into one solid whole, and in medicine it describes abnormal solid bodies — such as kidney or gallstones — that form from accumulated material within the body. Figuratively, writers use concretion to suggest ideas or interests hardening into a fixed, immovable mass. Formal and technical in register, it appears chiefly in geology, paleontology, medicine, and elevated prose rather than everyday conversation.
A hard, compact mass of matter formed by the aggregation or cementation of particles, especially a rounded mineral body developed within sedimentary rock.
"The cliff face was studded with iron-rich concretions that resisted weathering far better than the surrounding sandstone."
The process or result of coalescing into a single solid mass; also, in medicine, an abnormal stony mass formed within the body from accumulated material.
"Surgeons removed a painful concretion from the patient's salivary duct."
The plural is standard when referring to multiple mineral nodules, fossils preserved in them, or pathological masses; the singular often names the process itself.
"Amateur fossil hunters prize these concretions because splitting them open can reveal exquisitely preserved marine creatures."
Crack open some round stones found in sedimentary rock and you might find a fossil inside — those natural 'geode-like' balls are concretions, nature's own time capsules.
Reviewed by Deb Chak, Editor. AI-assisted content curated by RJS Tech Solutions LLP.
Etymology of concretion
"Concretion" derives from the Latin verb concrescere, meaning "to grow together," formed from com- ("together") and crescere ("to grow"). It entered English in the early modern period, likely in the 16th century, initially in medical contexts before broadening to describe geological masses. It shares its root with "concrete," which originally meant condensed or grown together, and with related words built on crescere such as "accrue" and "decrease."
Related word forms
How concretion is actually used
"Concretion" is a formal, largely technical word, most at home in geology, paleontology, and medicine; figurative uses describing abstract things coalescing into a rigid whole are literary rather than conversational. In everyday speech about building materials, "concrete" (the noun) or "concreting" would be used instead.
Easily confused with concretion
Concreting is the act or process of pouring and setting concrete in construction, while concretion is either the resulting solid mass (especially a natural geological one) or the general process of coalescing into one.
Concrescence refers specifically to biological growth together of parts or tissues, whereas concretion usually denotes an inorganic mineral mass formed by aggregation of particles.