information about an item, rather than the information in the item itself

Literally "about data", this terms refers to searchable index fields used to organize a body of larger documents, objects or content. For instance, in a searchable archive of image files, the "meta data" would refer to searchable fields such as artist name, title, year and so forth; the "content" would be the image file itself. For a news archive, the metadata would be the date, author and topic, and the content would be the actual story itself.

Descriptive information (e.g. title, description, audience, geospatial coverage, keywords) that can be used to describe, index and discover learning resources for particular user needs.

"structured information that describes, explains, locates, or otherwise makes it easier to retrieve, use, or manage an information resource" source: http://www.niso.org/news/releases/pr-Metadata-Primer.html