sub ‧ stra ‧ tum /ˌsʌbˈstrɑːtəm $ -ˈstreɪ-/ BrE AmE 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-/ BrE AmE noun ( plural substrata /-tə/) [countable]
technical a layer that lies beneath another layer, especially in the earth:
a substratum of rock
a social substratum
Longman Dictionary of Contemporary English. Longman - Словарь современного английского языка. 2012