Source : WordNet®

metadata
     n : data about data; "a library catalog is metadata because it
         describes publications"

Source : Free On-Line Dictionary of Computing

Metadata
     
         (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)

meta-data
     
         /me't*-day`t*/, or combinations of /may'-/ or
        (Commonwealth) /mee'-/; /-dah`t*/ (Or "meta data") Data about
        {data}.  In {data processing}, meta-data is definitional data
        that provides information about or documentation of other data
        managed within an application or environment.
     
        For example, meta-data 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.).  Meta-data may include
        descriptive information about the context, quality and
        condition, or characteristics of the data.
     
        Not to be confused with {Metadata}.
     
        (1997-04-06)