Summary of UMLS

Unified Medical Language System.
A research and development program initiated by the NATIONAL LIBRARY OF MEDICINE to build knowledge sources for the purpose of aiding the development of systems that help health professionals retrieve and integrate biomedical information. The three knowledge sources are the Metathesaurus, the Semantic Network, and the Specialist Lexicon. The version of UMLS, exampled here, consists of 7 vocabularies: ICPC (746 rows of health related concepts, terms with translations and synonyms),CSP (13454 rows), HL7 (10513 rows), ICD9CM (18500 rows),NCI (55402 rows),NDFRT (19241) rows, RXNORM (162887 rows).

CSP
Computer Retrieval of Information on Scientific Projects Thesaurus. (Anatomy,behavioral/social science, biology, chemical disease/disorder, food science/technology, medicine, named group,organism, physical science, technology/technique)
HL7
Vocabulary Versions 2.5 and 3.0
ICD9CM
The International Classification of Diseases: 9th revision, Clinical Modification
ICPC
International Classification of Primary Care (ICPC, ICPCBAQ, ICPCDAN, ICPCDUT, ICPCFIN, ICPCFRE, ICPCGER, ICPCHEB, ICPCHUN, ICPCITA, ICPCNOR,ICPCPOR, ICPCSPA, ICPCSWE) English,Basque,Danish,Dutch,Finnish,French,German,Hebrew,Hungarian,Italian,Norwegian,Portuguese, Spanish, Swedish Translations
NCI
The NCI Thesaurus is a product of NCI's Enterprise Vocabulary Services. The NCI Thesaurus is a rigorous, cancer-centric, formal reference vocabulary with true is_a taxonomic structure, polyhierarchy, inferred partonomy, and other features that make it suitable for supporting complex query operations against appropriately coded data repositories.
NDFRT
National Drug File - Reference Terminology
RxNorm
National Library of Medicine, RxNorm Project