substratum
noun [ C ] uk/səbˈstrɑː.təm/ us/səbˈstræt̬.əm/ substrata /səbˈstrɑː.tə/ /səbˈstræt̬.ə/
(LOWER LAYER)
geology specialized底土层;底土，心土
a layer of rock, soil, or similar material that is below another layer
A substratum of clay kept moisture close to the topsoil. 底土层的黏土使水分保持在表层土附近。
They planned to sink over twenty-five deep boreholes into the ground to assess the substrata. 他们计划在地下钻二十五个深井以评估底土层。
（位于一层物质下面的）底层，下层
a part or layer of something that is below another part or layer
Apply a substratum of lash powder and then quickly seal with a stroke of mascara. 涂一层睫毛粉打底，然后迅速用睫毛膏封住。
"Underclass" is used by sociologists to mean a substratum of society somewhere below the working class. 社会学家用"下层阶级"来指比工人阶级低的社会底层。
- More examples
- The spade dug up three inches of black soil with a substratum of yellow mud and clay.
- The rich alluvial soils provide an ideal substratum for growing rice.
- The Valmiki community is a substratum of the Dalit caste.
- There's a whole substratum of administrative positions.
(BASIS)
基础，本源；赋予属性的东西
something important from which something else develops, but that is not immediately obvious
There is a broad substratum of truth in what she says. 她所说的话有广泛的事实基础。
Would a jury conclude that a sufficient factual substratum existed for the comment? 陪审团是否会得出结论，认为评论存在足够的事实基础？
- More examples
- Many of the ancient mythical tales have a substratum of historical fact.
- There was a substratum of good feeling in her.
- The novel has a solid substratum of well-conceived minor characters.