Metalanguage

Metalanguage is language that is used to discuss, analyze, or describe another language, called the object language. It can be natural language or a formal language, and it operates at a higher level of description than the language it analyzes.

In logic, philosophy, and linguistics, the distinction between object language and metalanguage helps avoid semantic confusion. Statements about the syntax, semantics, or rules of an object language are made in a metalanguage. For example, stating that "in propositional logic, if p and q then r" is a statement about the object-language rules, usually expressed in English or with formal notation.

In linguistics and language education, metalinguistic discourse examines language itself—grammar, vocabulary, phonology, and usage. Metalinguistic awareness, for instance, is the ability to reflect on and manipulate language features, which supports language learning and reading.

In computer science and formal linguistics, metalanguages such as Backus-Naur Form or other formal grammars are used to define the syntax of programming languages or theories. The metalanguage provides the rules and symbols that describe the object language's structure.

Historically, the concept developed within logic and philosophy, notably in the work of Tarski and others, to articulate the separation between a theory's statements and the language used to discuss the theory. The term remains widely used to indicate discourse about language rather than language itself.