Online Dictionaries

•  Anderson's Dictionary of Law (1893)
• Bernstein's Dictionary of Bankruptcy Terminology
• Bouvier's Law Dictionary 1856 Edition
• Criminal Justice Today Glossary
• Criminology Today Glossary
• Criminal Law Glossary
• Divorce Law Dictionary
• Divorce Law Dictionary
• Duhaime's Law Dictionary • 
•  Everybody's Legal Glossary
• Merriam-Webster Legal Dictionary
• Glossary of Commercial Fraud
• Glossary of Human Rights Terms
•  International Law Glossary
• Juris International: Full text of model contracts, guidelines, and model clauses for international documents (English, French, Spanish)
• The Law Engine
• law.com Dictionary
• Legal Lexicon's Lyceum
• Immigration & Naturalization Service Glossary & Acronyms
•  Merriam-Webster's Law Dictionary
• Procurement Contract Glossary for Public Works and Government Services in Canada
• Publishing Contract Terms
• Glossary of Maritime Law Abbreviations, Definitions, Terms, etc.

Accounting  

• Accounting Glossary from "Financial Accounting" by Skousen et al.
• Accounting Glossary
• Glencoe Accounting Glossary
• Glossary of Auditing Terms
• Tax and Accounting Glossary
• Taxopedia Tax Glossary

Advertising

• Ad Planner Glossary
• A Dictionary of Terminology: Advertising
• Advertising Vocabulary

Business 

• Bernstein's Dictionary of Bankruptcy Terminology
• Business Glossary and Acronyms
• Definitions of Company Extensions around the World
• Dictionary of Management and Technology
• Dictionary of Occupational Titles (20,000+ listings)
• European Foundation Labor Relations Glossary
• Glossary of Commercial Fraud
• Harvey's Hypertextual Finance Glossary
• International Trading Dictionary
• NY Times Glossary of Financial and Business Terms(free subscription)
• Standard Industrial Classifications Index
• The WashingtonPost.com Business Glossary

English

• Merriam-Webster's Collegiate Dictionary, 10th Edition (yourDictionary's choice for a quick look-up)
• Xrefer Search Engine (Search all the Oxford Specialty Dictionaries at once)
• New Words in English
• American Heritage Dictionary, Thesaurus, and Quotes
• Cambridge Dictionary
• The Macquarie Dictionary (Australia's leading online dictionary) * 
• Dictionary of Difficult Words
• Newbury House Online Dictionary
• Early Modern English Dictionaries Database Search Utility
• English (gopher with a thesaurus)
• Grandiloquent Dictionary (1900 obscure and rare English words)
• The Jargon Dictionary
• Online Dictionary Database Query (DICT Group: free database)
• One-Look Dictionary-Search 500 dictionaries simultaneously
• On-line Dictionary (Webster's 1913, Wordnet, etc.)
• Oxford English Dictionary (subscription)
• Oxford Language Word Lists (about 25 languages but no translations)
• Yiddish Borrowings in English (OED)
• Wordnet English Dictionary and Thesaurus   
• The Wordsmyth English Dictionary-Thesaurus
• See also Multilingual Dictionaries
• See also English Dialects
• See also Specialty Dictionaries
• English Language Videos, Tapes, CDs, and Books
• English Pocket Electronic Dictionary

• YourDictionary.com • Specialty Dictionaries
• yourDictionary.com • Home Page
• Wordsmyth Welcome!
• Merriam-Webster OnLine

For related English language resources see:
English morphology
English grammars