substrate

1. (biochemistry) A substance acted upon, as by an enzyme.

2. (biology) A surface on which an organism grows, or to which an organism or an item is attached.Examples: "The rock surface of a rockpool is the substrate for a sessile organism such as a limpet."; "This definition [of "tool"] is not simple, but contains several elements. The tool must not be part of the animal's body (a beak is not a tool); the user must manipulate the tool in some way for it to realise its function; and, finally, a tool cannot be attached to the substrate. This is a fairly clear definition, but does seem to produce some rather arbitrary distinctions (Hansell 1987b). The spider Dinopis, for example, makes a small web which it holds in its legs, thrusting it down on passing ants. This is a tool, but all other webs, however complex, are not since they are anchored to the substrate. The woodpecker finch […] that uses a fine stick held in the beak to extract insect prey from wood, is a tool user, but a shrike […] that impales an insect on a thorn still attached to the bush is not."; "Detach/subtract [tasks involve] Severing a fixed attachment between environmental objects (or the substrate) or removing object(s) from another unattached object, so the latter is a more useful tool."

3. (linguistics) A language that is replaced in a population by another language and that influences the language imposed on its speakers.Antonyms: superstrate

4. (plating) A metal which is plated with another metal which has different physical properties.

5. (construction) A surface to which a substance adheres.