meta- is a concept in philosophy and linguistics in used for talking about things. Yea, thats pretty vague. Some examples are Metasyntax is the language used for talking about syntax. A metasearch engine is a search engine of search engines. Metafont is an abstraction of fonts used for describing various letters are displayed. Let us not forget about a metanode

This concept was first used by David Hilbert in the sense that we use it in metalanguage, metatheory, and metasystem. He introduced the term metamathematics to denote a mathematical theory of mathematical proof. That is, a mapping of proofs in the form of natural language text onto a set of texts in a formal logical language which makes it possible to treat proofs as precisely defined mathematical objects. This lead to Godel's Theorem.