stratum
STRAY-tum
/ˈstrɑːtəm/
A single layer of sedimentary rock or soil that is internally consistent and distinct from other layers.
While 'layer' is generic, 'stratum' implies a geological or sociological level that has been formed over time.
The story behind the word. Latin for 'something spread out', stratum originally referred to a bed-covering or a paved road (which is why we have the word 'street'). In geology, it describes the layers of the earth spread out over eons.
Word relationships
- layer: Layer is common and broad; stratum is specific to geology or formal social hierarchy.
- tier: Tier usually implies a vertical arrangement of identical things, like stadium seats, whereas stratum implies a distinct composition.
Commonly confused with
- strata: Strata is the plural form of stratum.
Word family
- stratify (verb): To form or arrange into layers.
- stratification (noun): The process of forming layers.
Collocations
- geological stratum
- social stratum
- rock stratum
Example sentences
- "The excavation revealed a thick stratum of clay that had prevented water from draining into the lower soil." Geological survey
- "The elite stratum of society often has different educational opportunities than the working class." Social science (metaphorical)
Memory hook
Think of 'straight' layers. A stratum is a straight layer of rock. One layer in the stack.
When not to use
Don't use it for a layer of clothing or a layer of cake; it's too formal and technical.
Fun facts
- The word 'street' actually comes from the Latin 'via strata', meaning a paved way.
Explore more words
strata, stratification, stratify, deposit, sedimentary, rock
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