Glossaries
Glossary Origin 1350–1400; Middle English glossarye < Latin glōssarium difficult word requiring explanation < Greek glōssárion, diminutive of glôssa tongue, language; later taken as a collection of such words, by construing suffix as Latin -ārium -ary;
(source: http://dictionary.reference.com/browse/glossary)
Systems engineering is a lot about communication. Communication means transmitting data. The receiver interprets data, sets it into a context to get information. Hence information is always in the eyes of the beholder. Data in communication between humans comprises of words. Therefore, successfull communication is only feasible if sender and receiver have the same understanding of the transmitted words.
ISO Concept Database contains terms, graphical symbols and codes (e.g., language codes) used in ISO standards and technical reports
https://cdb.iso.org/cdb/search.action
IEC Glossary contains terms used in IEC standards and technical reports
http://std.iec.ch/glossary
International Electrotecnical Vocabulary (IEV) contains the terms defined in IEC 60050 series of standards
http://www.electropedia.org/iev/iev.nsf/Welcome?OpenForm
SEVOCAB - Software and Systems Engineering Vocabulary
http://pascal.computer.org/sev_display/index.action
Object Management Group (OGM) Terms and Accornyms
http://www.omg.org/gettingstarted/terms_and_acronyms.htm
TOGAF Definitions
http://pubs.opengroup.org/architecture/togaf9-doc/arch/chap03.html
Dictionary.com
http://dictionary.reference.com
The Free Dictionary
http://www.thefreedictionary.com
WordNet search, Princeton University (not a glossary but a lexical database)
http://wordnetweb.princeton.edu/perl/webwn
Planguage Concept Glossary, by Tom Gilb and Kai Gilb
http://www.gilb.com/tiki-page.php?pageName=Competitive%20Engineering%20Glossary
IREB - A Glossary of Requirements Engineering Terminology
http://www.certified-re.de/fileadmin/IREB/Download/Homepage%20Downloads/IREB_CPRE_Glossary_11.pdf