NASA Thesaurus

"The Hierarchical Listing With Definitions contains all subject terms and USE cross references currently approved for use, and displays the full hierarchical structure for each term along with a definition when available. In addition, the listing has been developed to serve as an orthographic authority for upper/lowercase forms of all terms and cross references. The term-added date, displayed for all terms added after April 1988, is also given. The listing includes terms appearing in the NASA Thesaurus, Preliminary Edition (December 1967), the NASA Thesaurus Alphabetical Update (September 1971), the NASA Thesaurus (1982, 1985, 1988, 1994, and 1998 editions), and other terms approved for use through the end of January 2012. Over 18,400 terms, 4,300 definitions, and approximately 4,500 USE references are contained in the Hierarchical Listing With Definitions. The Rotated Term Display is a ready-reference tool that provides thousands of additional 'access points' to the thesaurus terminology. It contains the postable terms and nonpostable terms found in the Hierarchical Listing arranged in a KWIC (key-word-in-context) index. It is a useful companion to the Volume 1 listing, containing approximately 52,000 entries."