metadata

n. data about data, information known that makes it easy to access and use the data (e.g.: library catalog card, which includes information about the nature and location of a book); (Computers) descriptive information about data and documents (such as origin, size, formatting or different characteristics of a data)

Metadata is data about data. An item of metadata may describe an individual datum, or content item, or a collection of data including multiple content items. Metadata (sometimes written 'meta data') is used to facilitate the understanding, use and management of data. The metadata required for effective data management varies with the type of data and context of use. In a library, where the data is the content of the titles stocked, metadata about a title would typically include a description of the content, the author, the publication date and the physical location. In the context of a camera, where the data is the photographic image, metadata would typically include the date the photograph was taken and details of the camera settings. On a portable music player such as an Apple iPod, the album names, song titles and album art embedded in the music files are used to generate the artist and song listings, and are metadata. In the context of an information system, where the data is the content of the computer files, metadata about an individual data item would typically include the name of the field and its length. Metadata about a collection of data items, a computer file, might typically include the name of the file, the type of file and the name of the data administrator.
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Noun
1. data about data; "a library catalog is metadata because it describes publications"
(hypernym) data, information

<product> (Note: One unhyphenated word with initial capital; contrast meta data) A word coined by Jack E. Myers to represent current and future lines of products implementing the concepts of his MetaModel, and also to designate his company The Metadata Company that would develop and market those products.
A data and publication search performed when Myers coined the term, early in the summer of 1969, did not discover any use either of the word "metadata" or "meta data". Myers used the term in a 1973 product brochure and it is an Incontestable registered U.S. Trademark.
(1997-04-06)

Any kind of statistical information that defines or describes other data (e.g. attributes, structures, code lists, etc.).