/me't*-day`t*/, or combinations of /may'-/ or (Commonwealth) /mee'-/; /-dah`t*/ (Or "meta-data") Data about data. In data processing, metadata is definitional data that provides information about or documentation of other data managed within an application or environment.
For example, metadata would document data about data elements or attributes, (name, size, data type, etc) and data about records or data structures (length, fields, columns, etc) and data about data (where it is located, how it is associated, ownership, etc.). Metadata may include descriptive information about the context, quality and condition, or characteristics of the data.
A collection of metadata, e.g. in a database, is called a data dictionary.
Myers of The Metadata Company claims to have coined the term in 1969 though it appears in the book, "Extension of programming language concepts" published in 1968, by Philip R. Bagley. Bagley was a pioneer of computer document retrieval. "A survey of extensible programming languages" by Solntsseff and Yezerski (Annual Review in Automatic Programming, 1974, pp267-307) cites "the notion of 'metadata' introduced by Bagley".