Metalanguage is a form of language or set of terms used for the description or analysis of another language. We can use English as its own metalanguage (i.e. describing English grammar in English).
In linguistics, it denotes any technical language which describes the properties of language (discussed by Roman Jakobson in his essay Linguistics and Poetics, 1960). Metalanguage helps in describing the concepts, grammar, and objects associated with a particular programming language. It is also known as a ‘second-order’ language, which may be used to describe, explain, or interpret a ‘first-order’ language.
Given one metalanguage for one explanation it follows that there may be another in turn, and a metalanguage may replace a ‘first-order’ language. Each order of language implicitly relies on a metalanguage by which it is explained.
In his book Elements of Semiology (1967) Roland Barthes perceives that this could lead to an indefinite regression or aporia, which would ultimately undermine and destroy all metalanguages. In A Reader’s Guide to Contemporary Literary Theory (1985), Raman Selden summarizes the predicament very succinctly: This means that, when we read as critics, we can never step outside discourse and adopt a position invulnerable to a subsequent interrogative reading. All discourses, including critical interpretations, are equally fictive; none stands apart in the place of Truth.’