substratum
Longman Dictionary of Contemporary English 5++LDOCE 5++sub·stra·tum /ˌsʌbˈstrɑːtəm $ -ˈstreɪ-/ noun (plural substrata /-tə/) [countable] technicalHEG a layer that lies beneath another layer, especially in the earth 〔尤指土壤的〕下层，底（土）层 a substratum of rock 底层岩石 a social substratum 社会底层
Examples from the Corpus
substratum• A particular branch, the Grammatical Shastra, was formulated using the Sanskrit vocabulary as a substratum, with no ambiguity whatsoever.• Cultivation: An extremely undemanding plant as to its growing medium, and will grow almost in any substratum.• Cultivation: Very undemanding as to its growing medium, it will grow well on any substratum.• The distinction between substratum and entity also enables us to further specify the relations between Zeus and the world.• His books have tapped into a deep substratum of human religiosity.• Unlike the two previous species, this one prefers more organic content in its substratum.• They are suitable aquarium plants and are cultivated like Cryptocoryne species in a medium-rich substratum and water that is not too acid.• Research in other cell lines has suggested that the mechanical properties of the substratum are important in the maintenance of cellular differentiation.• The substratum of this experience is the mastery of a technique.sub·stra·tum nounChineseSyllable
that Corpus layer lies layer, especially a beneath in another
substratum
sub‧stra‧tum /ˌsʌbˈstrɑːtəm $ -ˈstreɪ-/
noun (plural substrata /-tə/) [countable]
technical a layer that lies beneath another layer, especially in the earth:
a substratum of rock
a social substratum
sub‧stra‧tum /ˌsʌbˈstrɑːtəm $ -ˈstreɪ-/
noun (plural substrata /-tə/) [countable]technical a layer that lies beneath another layer, especially in the earth: