substratum
noun /ˈsʌbstrɑːtəm/
/ˈsʌbstreɪtəm/
(plural substrata
(specialist) /ˈsʌbstrɑːtə/
/ˈsʌbstreɪtə/
)- a layer of something, especially rock or soil, that is below another layer
- a substratum of clay
- the substrata of society
Word Originmid 17th cent.: modern Latin, neuter past participle (used as a noun) of Latin substernere, from sub- ‘below’ + sternere ‘strew’. Compare with stratum.