stra·​tum | \ ˈstrā-təm How to pronounce stratum (audio) , ˈstra- How to pronounce stratum (audio) \
plural strata\ ˈstrā-​tə How to pronounce strata (audio) , ˈstra-​ \

Definition of stratum

1 : a bed or layer artificially made
2a : a sheetlike mass of sedimentary rock or earth of one kind lying between beds of other kinds
b : a region of the sea or atmosphere that is analogous to a stratum of the earth
c : a layer of tissue deep stratum of the skin
d : a layer in which archaeological material (such as artifacts, skeletons, and dwelling remains) is found on excavation
3a : a part of a historical or sociological series representing a period or a stage of development
b : a socioeconomic level of society comprising persons of the same or similar status especially with regard to education or culture
4 : one of a series of layers, levels, or gradations in an ordered system strata of thought
5 : a statistical subpopulation

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Synonyms for stratum


caste, class, estate, folk, gentry, order

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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.

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

Within the walls of this edifice, fountains of data lie waiting to be discovered by citizens representing all strata of life. Hillary Davis,, "Newport Beach Central Library turns the page on its first 25 years," 6 July 2019 And so stratigraphy — the study of layers (strata) of rock in relation to each other — was born. Gemma Tarlach, Discover Magazine, "Chronostratigraphy: How Scientists Unlock Deep Time," 30 June 2019 Instead, researchers have tried to probe the past by looking at sedimentary proxies: iron, carbon or sulfur compounds in geological strata with properties that can be measured and put into models to infer ancient oxygen levels. Quanta Magazine, "Rapid Oxygen Changes Fueled an Explosion in Ancient Animal Diversity," 9 May 2019 Hike through fields of dwarf pines to the shores of Lake Nassbodensee, crossing over alternating strata of calciferous and crystalline rock. National Geographic, "Hiking the Alpe-Adria Trail through Austria, Slovenia, and Italy," 12 June 2019 The room is divided into disciplines, akin to a NASA mission control room, with engineers in one section, payload specialists in another, and a stratum of officers overseeing the checklists. Joe Pappalardo, Popular Mechanics, "Inside the Locked Rooms Where They Protect GPS," 22 Mar. 2019 Or perhaps the mayor is thinking of Ken Langone, the Home Depot founder, who has donated hundreds of millions of dollars to the New York University Medical Center that treats patients of all incomes and social strata. The Editorial Board, WSJ, "Money ‘in the Wrong Hands’," 13 Jan. 2019 The same could be seen with other companies catering to the same economic strata, such as Vail Resorts . Elizabeth Winkler, WSJ, "Nordstrom Has Rich-People Problems," 16 Jan. 2019 Alex Makes the Strata I'm hooked on Gale Gand's strata. Alexandria Abramian-mott, House Beautiful, "Gale Gand's Recipe for Strata," 3 Jan. 2012

These example sentences are selected automatically from various online news sources to reflect current usage of the word 'stratum.' Views expressed in the examples do not represent the opinion of Merriam-Webster or its editors. Send us feedback.

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First Known Use of stratum

1599, in the meaning defined at sense 1

History and Etymology for stratum

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

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Statistics for stratum

Last Updated

16 Jul 2019

Look-up Popularity

Time Traveler for stratum

The first known use of stratum was in 1599

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More Definitions for stratum



English Language Learners Definition of stratum

: one of usually many layers of a substance (such as rock)
: a level of society made up of people of the same rank or position


stra·​tum | \ ˈstrā-təm How to pronounce stratum (audio) , ˈstra-\
plural strata\ -​tə \

Kids Definition of stratum

: layer entry 1 sense 1 a stratum of rock


stra·​tum | \ ˈstrāt-əm How to pronounce stratum (audio) , ˈstrat- How to pronounce stratum (audio) \
plural strata\ ˈstrāt-​ə How to pronounce strata (audio) , ˈstrat-​ How to pronounce strata (audio) \

Medical Definition of stratum

1 : a layer of tissue a deep stratum of the skin
2 : a statistical subpopulation

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Comments on stratum

What made you want to look up stratum? Please tell us where you read or heard it (including the quote, if possible).


something desired as essential

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