What does stratum mean?
A stratum is a distinct layer or level. In geology, the word refers to a layer of rock, soil, or sediment, and its plural, strata, is commonly used for a sequence of such layers. The word also has a social meaning: a stratum can be a group within a larger hierarchy, such as an occupational, economic, or social class. In this sense, “stratum” is often more formal than “group” or “level” and may imply that members share broadly similar circumstances or status. The word is useful when discussing both physical layers and the hierarchical organization of societies, institutions, or other systems. Its Latin origin, meaning a layer or pavement, reflects its long history of describing surfaces arranged one above another.
nounA layer or level of material, especially a distinct layer of rock or soil. By extension, a stratum is a level within a system or society, such as an economic or social group.
- A distinct layer of rock, soil, sediment, or other material.
- A level or layer within a larger system, especially a social, economic, or occupational group.
- A group of organisms or fossils occurring at a particular level in a geological formation.
"The fossil was embedded in a sedimentary stratum that had been undisturbed for millions of years."
"The cliff exposes several clearly visible strata of sedimentary rock."
"The study found that educational opportunities varied markedly between different social strata."
“Strata” is the standard plural in geological and figurative contexts. “Stratums” is also accepted, particularly in general writing, but is less usual.
"The exposed strata reveal a long history of deposition and erosion."
From the Latin for a paved layer, “stratum” went from describing layers of rock to describing the hidden layers of society.
Reviewed by Deb Chak, Editor. AI-assisted content curated by RJS Tech Solutions LLP.
Where does stratum come from?
“Stratum” comes from Latin, where it referred to a layer, bed, or pavement. English borrowed the word in the 17th century for a layer of rock or other material, and it was later extended to social and economic levels. The same Latin root underlies words such as “stratify,” “stratification,” and “stratigraphy,” all of which involve arranging or studying layers.
Related word forms
How stratum is actually used
In geology, “stratum” is a technical term, with “strata” commonly used for multiple layers. In social and economic contexts, it often suggests a relatively stable group defined by status, wealth, occupation, or access to resources.
Easily confused with stratum
Stratum is the singular form, while strata is the usual plural used for multiple layers or groups.
Stratum refers to a layer or level, whereas stature refers to height, standing, or importance.