stra·​tum ˈstrā-təm How to pronounce stratum (audio) ˈstra- How to pronounce stratum (audio)
plural strata ˈstrā-tə How to pronounce stratum (audio) ˈstra- How to pronounce stratum (audio)
: a bed or layer artificially made
: a sheetlike mass of sedimentary rock or earth of one kind lying between beds of other kinds
: a region of the sea or atmosphere that is analogous to a stratum of the earth
: a layer of tissue
deep stratum of the skin
: a layer in which archaeological material (such as artifacts, skeletons, and dwelling remains) is found on excavation
: a part of a historical or sociological series representing a period or a stage of development
: a socioeconomic level of society comprising persons of the same or similar status especially with regard to education or culture
: one of a series of layers, levels, or gradations in an ordered system
strata of thought
: a statistical subpopulation
Is strata singular or plural?: Usage Guide

The plural strata has occasionally been used as a singular since the 18th century and is sometimes given the plural stratas.

there was a strata of Paris which mere criticism of books fails to get hold of Ezra Pound
a Roman burial ground suggests stratas of corruption and decay Connie Fletcher, Booklist

Current evidence shows senses 2, 3b, and 4 so used, with sense 3b the most common. Singular strata is persistent but not frequent. Strata may someday establish itself as a singular like agenda, but that use is still not established. We should also point out that there is a derivative culinary term strata, entered separately in this dictionary, which has a singular sense, denoting a layered and baked dish whose ingredients include eggs, bread, and cheese. For the edible strata the logical and usual plural is stratas, but strata is also used as a secondary plural (as in "several ham and cheese strata"), presumably by those for whom stratas looks like an error.

Did you know?

In geology, a stratum is a layer of rock or soil that is distinct from those above and below it. Rock and soil strata (notice the plural form) can be seen in road cuts, cliffs, quarries, riverbanks, and sand dunes, and in pieces of limestone, slate, and shale. Archaeologists digging in historical sites are careful to note the stratum where each artifact is found. Earth scientists divide the earth's atmosphere into strata, just as oceanographers divide the ocean's depths into strata. And for social scientists, a stratum is a group of people who are similar in some way, such as education, culture, or income.

Examples of stratum in a Sentence

the lower strata of society have been hit especially hard by this economic downturn the level of writing in that pop novel is several strata beneath that of serious fiction
Recent Examples on the Web That’s about to become an increasingly real problem, particularly for those with parents in the middle-income stratum. Sarita A. Mohanty, Fortune, 30 Dec. 2023 Face it, after 40-some years spent in the rafters of rad, few humans could peel back the stratum of underground rock to such delicious degree as Thurston Moore. Jonathan Rowe, SPIN, 23 Jan. 2024 With these and the release of Gladiator 2 next year, Mescal is on the precipice of catapulting into another stratum of fame and cementing his status among the next generation’s great film talents. Harper's BAZAAR, 16 Aug. 2023 Sitting in Los Angeles traffic on a Friday afternoon, Joseph Friedman, an addiction researcher at the University of California, Los Angeles, spouted off a series of terrifying statistics about fentanyl deaths ripping through seemingly every stratum of American life. Zachary Siegel, The New Republic, 27 June 2023 Since most mass shooters in the United States would be considered middle class by Latin American standards, the kinship bonds among this stratum of society may be most relevant to explaining lower rates of mass shootings. Paul Hirschfield, Foreign Affairs, 29 July 2022 And yet, as the search for clandestine meanings intensifies everywhere, the distinction has collapsed to include anything that lies just beneath the surface, and what was once the subtext — a stratum of fandom accessible only to the most loyal and discerning observers — has become the context. Nick Haramis, New York Times, 13 Jan. 2023 Advertisement The public teems at these unscripted remarks because the justices occupy a curious stratum in the country’s political pyramid, able to change the course of history with their pens but accountable, really, only to themselves. Jesús Rodríguez, Washington Post, 23 June 2023 But a significant stratum of society—teachers, for example—are forced to participate in public acts of support, such as the patriotic lessons that are now mandatory in schools on Mondays. Andrei Kolesnikov, Foreign Affairs, 7 Apr. 2023

These examples are programmatically compiled from various online sources to illustrate current usage of the word 'stratum.' Any opinions expressed in the examples do not represent those of Merriam-Webster or its editors. Send us feedback about these examples.

Word History


New Latin, from Latin, spread, bed, from neuter of stratus, past participle of sternere to spread out — more at strew

First Known Use

1599, in the meaning defined at sense 1

Time Traveler
The first known use of stratum was in 1599

Dictionary Entries Near stratum

Cite this Entry

“Stratum.” Dictionary, Merriam-Webster, Accessed 16 Apr. 2024.

Kids Definition


stra·​tum ˈstrāt-əm How to pronounce stratum (audio) ˈstrat- How to pronounce stratum (audio)
plural strata -ə How to pronounce stratum (audio)
: a layer of a substance
especially : one of a series of layers
a rock stratum
a stratum of earth
the deep stratum of the skin
: a level of society consisting of persons of the same or similar rank or position

Medical Definition


stra·​tum ˈstrāt-əm How to pronounce stratum (audio) ˈstrat- How to pronounce stratum (audio)
plural strata ˈstrāt-ə How to pronounce stratum (audio) ˈstrat- How to pronounce stratum (audio)
: a layer of tissue
a deep stratum of the skin
: a statistical subpopulation

More from Merriam-Webster on stratum

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