Substrates meaning : What an enzyme acts upon. A surface on which an organism grows, or to which an organism or an item is attached. An underlying layer; a substratum. A language that is replaced in a population by another language and that influences the language imposed on its speakers. (plating) A metal which is plated with another metal which has different physical properties. A surface to which a substance adheres. The substance lining the bottom edge of an enclosure.