1. an indigenous language that contributes features to the language of an invading people who impose their language on the indigenous population

e.g. the Celtic languages of Britain are a substrate for English

Synonym: substratum

2. any stratum or layer lying underneath another

Synonym: substratum

3. a surface on which an organism grows or is attached

e.g. the gardener talked about the proper substrate for acid-loving plants

Synonym: substratum

4. the substance that is acted upon by an enzyme or ferment