substratum的復數形
Substratum \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.