substratum (n.)

• air
• atom
• band
• base
• basement
• basis
• bed
• bedding
• bedrock
• belly
• belt
• bottom
• breech
• buttocks
• component
• constituent
• core
• course
• deck
• downside
• earth
• element
• fire
• floor
• flooring
• footing
• foundation
• fundament
• fundamental
• gallery
• ground
• grounds
• groundwork
• hardpan
• hyle
• hypostasis
• infrastructure
• layer
• ledge
• level
• material
• materiality
• matter
• measures
• meat
• molecule
• monad
• nature
• overlayer
• pavement
• plenum
• principle
• radical
• root
• rudiment
• seam
• seat
• shelf
• sill
• stage
• step
• story
• stratum
• stuff
• substance
• substrate
• substructure
• superstratum
• thickness
• tier
• topsoil
• underbelly
• undercarriage
• underside
• understructure
• water
• zone