S: (n) substrate, substratum (a surface on which an organism grows or is attached) "the gardener talked about the proper substrate for acid-loving plants"
S: (n) surface (the extended two-dimensional outer boundary of a three-dimensional object) "they skimmed over the surface of the water"; "a brush small enough to clean every dental surface"; "the sun has no distinct surface"
S: (n) stratum (one of several parallel layers of material arranged one on top of another (such as a layer of tissue or cells in an organism or a layer of sedimentary rock))
S: (n) substrate, substratum (an indigenous language that contributes features to the language of an invading people who impose their language on the indigenous population) "the Celtic languages of Britain are a substrate for English"