What is another word for "substratum"?

Roget's Thesaurus (1911) lists these synonyms for "substratum": abdomen, abdominal, and, article, backbone, base, baseboard, based, basement, basis, bed, being, belly, bilge, blood, board, bodily, body, bosom, bottom, breast, brute, built, cave, center, centerboard, circumscribe, coat, coeliac, concavity, condition, contents, corporal, corporality, corporeal, corporeity, corpus, course, cover, covering.