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 (strā′tə, străt′ə)
A plural of stratum.


(Geological Science) a plural of stratum
Usage: Strata is sometimes wrongly used as a singular noun: this stratum (not strata) of society is often disregarded


(ˈstreɪ təm, ˈstræt əm)

n., pl. stra•ta (ˈstreɪ tə, ˈstræt ə) stra•tums.
1. a layer of material, naturally or artificially formed, often formed one upon another.
2. layer; level: an allegory with many strata of meaning.
3. a single bed of sedimentary rock, generally consisting of one kind of matter representing continuous deposition.
4. a layer of tissue; lamella.
5. a layer of vegetation in a plant community.
6. a layer of the ocean or the atmosphere distinguished by natural or arbitrary limits.
7. a level or grade of a people or population esp. with reference to social position and education: the lowest stratum of society.
[1590–1600; < Latin strātum literally, a cover, n. use of neuter of strātus, past participle of sternere to spread, strew]
usage: The usual singular of this noun, taken from Latin, is stratum: the lowest stratum in society. The plural is strata: Several strata of settlement were discovered in the evacuation. Occasionally strata occurs as a singular and stratas as a plural. Neither of these uses is well established, and they are often regarded as errors. See also agenda, criterion, media.
References in classic literature ?
On the absence of intermediate varieties at the present day -- On the nature of extinct intermediate varieties; on their number -- On the vast lapse of time, as inferred from the rate of deposition and of denudation -- On the poorness of our palaeontological collections -- On the intermittence of geological formations -- On the absence of intermediate varieties in any one formation -- On the sudden appearance of groups of species -- On their sudden appearance in the lowest known fossiliferous strata.
Forbes, in a greater depth of water than from 40 to 250 feet; but they are now covered with sea-deposited strata from 800 to 1000 feet in thickness: hence the bed of the sea, on which these shells once lived, must have sunk downwards several hundred feet, to allow of the accumulation of the superincumbent strata.
The gases of the powder, expanded by heat, forced back the atmospheric strata with tremendous violence, and this artificial hurricane rushed like a water-spout through the air.
During the next three hours we passed through ten miles of ice, eventually emerging into another series of ammonia-impregnated strata, where the mercury again fell to ten degrees below zero.
The lower strata of the middle class -- the small tradespeople, shopkeepers, retired tradesmen generally, the handicraftsmen and peasants -- all these sink gradually into the proletariat, partly because their diminutive capital does not suffice for the scale on which Modern Industry is carried on, and is swamped in the competition with the large capitalists, partly because their specialized skill is rendered worthless by the new methods of production.
This stifling heat, penetrating through the partitions of the projectile, is produced by its friction on the atmospheric strata. It will soon diminish, because we are already floating in space, and after having nearly stifled, we shall have to suffer intense cold.
Any overheated motor may of course "seize" without warning; but so many complaints have reached us of accidents similar to yours while shooting the Aurora that we are inclined to believe with Lavalle that the upper strata of the Aurora Borealis are practically one big electric "leak," and that the paralysis of your engines was due to complete magnetization of all metallic parts.
One circle was her husband's government official set, consisting of his colleagues and subordinates, brought together in the most various and capricious manner, and belonging to different social strata. Anna found it difficult now to recall the feeling of almost awe-stricken reverence which she had at first entertained for these persons.
Hitherto the various strata of rock had exhibited a gentle elevation toward the southwest, but here everything appeared to have been subverted, and thrown out of place.
The entire member seems a dense webbed bed of welded sinews; but cut into it, and you find that three distinct strata compose it: --upper, middle, and lower.
On the whole we get on pretty smoothly in our domestic relations, except in the lower strata of the Military Classes.
If we do NOT know them all--if Nature has still secrets in the deeps for us, nothing is more conformable to reason than to admit the existence of fishes, or cetaceans of other kinds, or even of new species, of an organisation formed to inhabit the strata inaccessible to soundings, and which an accident of some sort has brought at long intervals to the upper level of the ocean.