UMBEL (Upper Mapping and Binding Exchange Layer)  is a lightweight ontology for relating Web content and data to a standard set of 20,000 subject concepts. Based on OpenCyc , these subject concepts have defined relationships between them, and can act as semantic binding nodes for any data or Web content. A further 1.5 million named entities have been extracted from Wikipedia and mapped to the UMBEL reference structure with cross-links to YAGO  and DBpedia . The system can easily be extended with additional dictionaries of named entities, including ones specific to enterprises or domains.
UMBEL is provided as open source under the Creative Commons 3.0 Attribution-Share Alike license. The complete ontology with all subject concepts, definitions, terms and relationships can be freely downloaded [see 5]. All subject concepts and named entities are available as Linked Data [see 5]. Five volumes of documentation  are also available.
The release is accompanied by about a dozen Web services  for using or manipulating UMBEL, along with a new introductory slide show . Additional release information may be found on Fred’s  or my  separate blog postings. We welcome those with interest or suggestions for improvements to do so through the UMBEL discussion forum . We will shortly be putting easier services online for such input.
So, enjoy! We look forward to your commentary, suggestions and putting UMBEL under production-grade stress. We know will be doing the same!