\Sub*stra"tum\, n.; pl. {Substrata}. [L. substratus,
p. p. of substernere to strew under; sub under + sternere to
strew. See {Stratum}.]
1. That which is laid or spread under; that which underlies
   something, as a layer of earth lying under another;
   specifically (Agric.), the subsoil.

2. (Metaph.) The permanent subject of qualities or cause of
   phenomena; substance.