Definition of stratum in English:

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Pronunciation: /ˈstrādəm/
Pronunciation: /ˈstradəm/

noun (plural strata /ˈstrātə/ /ˈstra-/)

1A layer or a series of layers of rock in the ground: a stratum of flint
More example sentences
  • Carboniferous to Cretaceous strata are exposed in an extensive series of outcrops along the east coast of Greenland.
  • The deposition of Palaeogene siliciclastic shelf strata in the Wessex Basin cannot be interpreted exclusively in terms of fluctuations in relative sea level.
  • Additional control on the subsurface continuity of the strata is provided by seismic data.
layer, vein, seam, lode, bed
1.1A thin layer within any structure: thin strata of air
More example sentences
  • Cody's hypothesis would require that an individual remains within a smaller stratum in the high-density layer than in the low-density layer.
  • The decision to baptize chips under a thin liquid stratum will allow the making of circuits with features that measure the breadth of a virus.
  • If a school refused to participate, they selected a replacement school within the same stratum.
2A level or class to which people are assigned according to their social status, education, or income: members of other social strata
More example sentences
  • Women, of all ages, education, and social strata love the gossip magazines!
  • There is no question that the working class must strive to win the support of other classes and intermediate social strata in the struggle against global capitalism.
  • The approaches of different countries, social strata and classes differ as well.
level, class, echelon, rank, grade, group, set;
dated station, estate
2.1 Statistics A group into which members of a population are divided in stratified sampling.
Example sentences
  • Because the survey used a complex stratified design with differences in sampling fractions among strata, the unweighted sample is not representative of the target population.
  • The overall household rate was increased by sampling disproportionately from the strata with larger proportions of households.
  • Sampling fractions for different strata were used to compute the number of subjects in each subgroup.


In Latin, the word stratum is singular and its plural form is strata. In English, this distinction is maintained. It is therefore incorrect to use strata as a singular: a new stratum was uncovered (not a new strata was uncovered). It is also wrong to create the form stratums or stratas as the plural: a series of overlying strata (not overlying stratums or overlying stratas).


Late 16th century (in the sense 'layer or coat of a substance'): modern Latin, from Latin, literally 'something spread or laid down', neuter past participle of sternere 'strew'.

Words that rhyme with stratum

desideratum, erratum, post-partum

For editors and proofreaders

Syllabification: stra·tum

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