Substratum
Part of speech: noun
Definition: A layer that lies underneath another The underlying cause or basis of something
Substrate
Part of speech: noun
Definition: The material or substance on which an enzyme acts.A surface on which an organism grows or is attached e.g. the rock surface of a rockpool is the substrate for a sessile organism such as a limpet.An underlying layer; a substratum.An indigenous language that contributes features to the language of an invading people who impose their language on the indigenous population.A metal which is plated with another metal which has different physical properties.A surface to which a substance adheres.