substratum
[noun]
Synonyms: basis, base, bedrock, footing, foundation, ground, groundwork, infrastructure, root, underpinning, bottom, seat, substruction, substructure, understructure

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Related Words: core, meat, stuff, substance

[TahlilGaran] English Synonym Dictionary ▲

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

[TahlilGaran] Dictionary of Contemporary English ▲