Definition of "substrate" [sub•strate]

• The material or substance on which an enzyme acts. (noun)
• Biology A surface on which an organism grows or is attached. (noun)
• An underlying layer; a substratum. (noun)
• Linguistics An indigenous language that contributes features to the language of an invading people who impose their language on the indigenous population. (noun)

American Heritage(R) Dictionary of the English Language, Fifth Edition. Copyright (c) 2011 by Houghton Mifflin Harcourt Publishing Company. Published by Houghton Mifflin Harcourt Publishing Company. All rights reserved.

• "In a breakthrough discovery, we found that the target substrate is covalently modified by multiple moieties of APF-1, a reversible modification that renders the protein substrate susceptible to degradation."
• "When a language, Latin in this case, imposes on a preexisting one, as Latin did Celtic, the original local language is called a substrate language: it sits on a stratum under sub the new language."
• "Typically, the light in the substrate is internally reflected and runs parallel and not perpendicular."