Quick Reference Resources: Dictionaries & Thesauri

General

• Oxford Reference Online
  Provides access to Oxford University Press dictionaries and other reference resources on a wide variety of topics including arts, computing, history, languages, law, literature and quotations, religion, sciences, and social sciences.
• Dictionaries from Librarians' Internet Index

Abbreviations & Acronyms

• Abbreviations and Acronyms of the U.S. Government
• Acronym Finder
• BABEL: A Glossary of Computer Oriented Abbreviations and Acronyms
• Instant Messaging Acronyms and Shorthand
• Internet Acronym Server
• Journal Abbreviation Sources ("All That JAS")
• Military Acronyms and Glossaries

English

• Merriam Webster's Collegiate Dictionary and Thesaurus
• OED: Oxford English Dictionary 

Foreign Language

• Babel Fish Translation
• Foreign language dictionaries from Yahoo
• Language dictionaries from yourDictionary.com
• WordReference.com

Law

• Law.com Dictionary

Medical

• MedlinePlus Medical Dictionary
• Medterms.com Medical Dictionary
• Stedman's Medical Dictionary 
• Taber's Cyclopedic Medical Dictionary 
• Mosby's Medical, Nursing, and Allied Health Dictionary 

Slang

• Slang Dictionaries from Yahoo

Subject

• Bio Tech's Life Science Dictionary
• Concise Oxford Dictionary of Mathematics
• Dictionary of Computing
• Dictionary of Phrase and Fable
• Grove Art Online
• Grove Music Online
• New Palgrave Dictionary of Economics Online
• Specialty dictionaries from yourDictionary.com
• Whatis?com dictionary of Information Technology