a substratum; foundation
(materials science), the material on which a process is conducted
(biology), the natural environment in which an organism lives, or the surface or medium on which an organism grows or is attached
(chemistry), the catalytic material upon which chemical species react
(marine biology), the earthy material that exists in the bottom of a marine habitat, like dirt, rocks, sand, or gravel
(printing), the base material that images will be printed onto
