substrate

Concise Oxford English Dictionary © 2008 Oxford University Press:
substrate /ˈsʌbstreɪt/

▶noun

• 1 the surface or material on which an organism lives, grows, or feeds.

• 2 the substance on which an enzyme acts.

• 3 a surface on which something is deposited or inscribed, e.g. the silicon wafer used to manufacture integrated circuits.

– origin C19: anglicized form of substratum.