An ELT Glossary : Metalanguage

Definition : The specialist, technical terms used to talk about language.

Examples : The terms included in this glossary include metalanguage concerned with grammar, lexis, phonology and discourse. Eg the underlined words in :

Do is a primary auxiliary which acts as operator in the verb phrase for verb forms with simple aspect.

If you use metalanguage in the classroom with a new class, always check that students understand it.