noun stra·tum \ ˈstrā-təm , ˈstra- \
|Updated on: 30 Jul 2018

Definition of stratum

plural strata play \ˈstrā-tə, ˈstra-\
1 : a bed or layer artificially made
2 a : 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
3 a : 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

Is strata singular or plural?

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 FletcherBooklist
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.

Examples of stratum in a Sentence

  1. the lower strata of society have been hit especially hard by this economic downturn

  2. the level of writing in that pop novel is several strata beneath that of serious fiction

Recent Examples of stratum from the Web

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.

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.

Origin and Etymology of stratum

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

Other Archaeology Terms

STRATUM Defined for English Language Learners


Definition of stratum for English Language Learners

  • : 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

STRATUM Defined for Kids


noun stra·tum \ ˈstrā-təm , ˈstra- \

Definition of stratum for Students

plural strata \-tə\
: 1layer 1
  • a stratum of rock

Medical Dictionary


noun stra·tum \ ˈstrāt-əm , ˈstrat- \

medical Definition of stratum

plural strata play \ˈstrāt-ə, ˈstrat-\
1 : a layer of tissue
  • a deep stratum of the skin
2 : a statistical subpopulation

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