A bibliographic index is an "open-end finding guide to the literature of an academic field or discipline (example: Philosopher's Index), to works of a specific literary form (Biography Index) or published in a specific format (Newspaper Abstracts), or to the analyzed contents of a serial publication (New York Times Index). Indexes of this kind are usually issued in monthly or quarterly paperback supplements, cumulated annually.
Some bibliographic indexes are also published online, in which case they are called bibliographic databases
Source : http://en.wikipedia.org/wiki/Bibliographic_index [visited 2010-09-15]
A bibliographic database is a database of bibliographic records, an organized digital collection of references to published literature, including journal and newspaper articles, conference proceedings, reports, government and legal publications, patents, books, etc. In contrast to library catalogue entries, a large proportion of the bibliographic records in bibliographic databases describe analytics (articles, conference papers, etc.) rather than complete monographs, and they generally contain very rich subject descriptions in the form of keywords, subject classification terms, or abstracts.
A bibliographic database may be general in scope or cover a specific academic discipline. A significant number of bibliographic databases are still proprietary, available by licensing agreement from vendors, or directly from the abstracting and indexing services that create them.
Many bibliographic databases evolve into digital libraries, providing the full-text of the indexed contents. Others converge with non-bibliographic scholarly databases to create more complete disciplinary search engine systems, such as Chemical Abstracts or Entrez
Source : http://en.wikipedia.org/wiki/Bibliographic_database [visited 2010-09-15]
In the hierachy of a thesaurus, relationship between a term and a more generic term.