What does sediment mean?
Sediment is the solid material that settles from a liquid or accumulates through deposition. It may consist of fine particles such as clay, silt, and sand, or of larger fragments of mineral and organic matter. In geology, successive deposits of sediment can form sedimentary layers and, when hardened into rock, sedimentary rock. The word also names the accumulated material itself, as when a river carries sediment toward a reservoir or geological evidence is preserved in sediment deposits. Sediment is usually treated as an uncountable noun when referring to a substance or process, but separate layers or deposits can be counted as sediments. As a verb, “to sediment” means to settle or form a deposit, though this use is less common. The word is important across environmental science, geology, construction, and water management, where the movement and accumulation of sediment can affect ecosystems, landforms, and infrastructure.
Solid particles or other material deposited by water, wind, ice, gravity, or other natural processes, especially material that settles in layers or at the bottom of a liquid.
"The reservoir has lost substantial capacity as sediment accumulated behind the dam."
Commonly used as an uncountable mass noun; the plural “sediments” is appropriate for distinct deposits or layers.
To settle or accumulate as sediment.
"Particles sediment rapidly when the water becomes still."
This verb is relatively uncommon and is chiefly used in technical, formal, or literary contexts.
Usually used when referring to distinct deposits, layers, or masses of sediment.
"Geologists compared sediments from several ancient river channels."
Every layer of sediment is a timestamp: buried beneath later deposits, it can preserve a record of ancient environments and life.
Reviewed by Deb Chak, Editor. AI-assisted content curated by RJS Tech Solutions LLP.
Where does sediment come from?
The word comes through French from Latin sedimentum, meaning “a settling” or “sediment,” which was derived from sedere, “to sit,” with the suffix -mentum. The underlying image is of material coming to rest or settling in place. English cognates such as subside, reside, preside, and sessile ultimately relate to the same Latin root for sitting.
Related word forms
How sediment is actually used
As a noun, sediment is commonly used as an uncountable mass noun, although the plural “sediments” is used for distinct deposits or layers. The verb is relatively uncommon and is most often encountered in technical or formal writing.
Easily confused with sediment
Sediment is the deposited material itself, whereas sedimentary describes a rock or process formed through the accumulation and lithification of deposited material.