NASA Thesaurus

The NASA Thesaurus contains the authorized subject terms by which the documents in the NASA Aeronautics and Space Database are indexed and retrieved. The scope of this controlled vocabulary includes not only aerospace engineering, but all supporting areas of engineering and physics, the natural space sciences (astronomy, astrophysics, and planetary science), Earth science, and to some extent, the biological sciences. The Thesaurus contains over 18,270 terms, 4,287 definitions, and 4,470 USE references. Terms are organized within a hierarchical structure, and also include ‘related terms’ lists.