AskOxford.com

For questions on English grammar, spelling, and usage; to search a dictionary of words, names or quotations; for help with writing; for crosswords and puzzles.
http://www.askoxford.com/

Ultralingua Online Dictionary

Searchable dictionary of the English language, with standard, reverse and phonetic lookup. Also links to a range of other language resources.
http://www.ultralingua.net/

Dictionary.net

Comprehensive dictionary database of word and phrase definitions from 8 different sources.
http://www.dictionary.net/

The Beet Foundation

General purpose online English language dictionary and Thesaurus.
http://beetfoundation.com/words/

The American Heritage Dictionary of the English Language

Online publication of the 4th edition. Featuring audio word pronunciations, illustrations.
http://www.bartleby.com/61/

HyperDic

Based on the WordNet lexical database and thesaurus, this dictionary covers only a selection of the most frequent English words. Includes synonyms, antonyms, examples and pronunciation, and links between related words.
http://www.hyperdic.net/

SmartDictionary.com

Supports both searching and browsing and encourages user contributions.
http://www.smartdictionary.com/

The Rap Dictionary

Hip-hop slang and also contains a list of hip-hop artists and their real names.
http://www.rapdict.org/terms/a

The English-to-American Dictionary

A humo(u)rous resource for Americans learning British/Scottish English.
http://english2american.com/

DataSegment.com: Online Dictionary

Find definitions by alphabetical browsing or word lookup. Powered by several print dictionaries.
http://onlinedictionary.datasegment.com/

Bibliomania: Webster's Unabridged Dictionary of 1913

Forms version. Allows browsing headwords.
http://www.bibliomania.com/2/3/257/frameset.html

The Wordsworth Compendium

Program containing over 516,000 English words and phrases to solve word puzzles. Useful for the search and manipulation of words in all aspects of logological activities.
http://dictionary-thesaurus.com/

Dictionary.com

Online English dictionary, thesaurus and reference guide. Includes word games, online translator, and word of the day feature.
http://dictionary.reference.com/

Die.net Online Dictionary

Cross-referenced definitions, spelling correction, and searches from WordNet, Webster's, and a variety of specialized sources. Supports regular expressions and the DICT protocol.
http://dict.die.net/

AnsMe.com Dictionary

Finds definitions, similar-sounding words, relations, words that rhyme, and translations.
http://dictionary.ansme.com/

Freesearch Dictionary

A British English dictionary powered by the Cambridge University Press that contains around 150,000 words. The site offers a search feature or can be browsed by letter.
http://www.freesearch.co.uk/dictionary

An Internet Dictionary.

Online dictionary lets you search for definitions, cross-references English dictionaries based on multiple databases. Cross-references English dictionaries based on multiple databases. Downloadable software gives the ability to integrate the dictionary wi
http://Dict.AIEdu.com

Plan of an English Dictionary (1747)

Letter written by Samuel Johnson to the Earl of Chesterfield setting out his plan for an English Dictionary.
http://andromeda.rutgers.edu/~jlynch/Texts/plan.html

Longman Web Dictionary

Searchable dictionary of contemporary english
http://www.ldoceonline.com/

Word Sytes

Use this online dictionary to search for definitions in WordNet, Webster's and many other databases.
http://word.sytes.org/

WordIQ Dictionary

Searchable definitions available in a variety of dictionaries including Webster's, a legal dictionary, a dream dictionary, and an encyclopedia.
http://www.wordIQ.com/dictionary.html

Vdictionary.com

Searchable English language dictionary shows results in synonym sets.
http://www.vdictionary.com/

Dictionary of Indian English

Regionalisms defined.
http://www.vsubhash.com/desienglish.asp

Macmillan English Dictionaries

Resource site for the Macmillan range of dictionaries.
http://www.macmillandictionary.com/

Gutenberg.com

A Concise Dictionary of Middle English From A.D. 1150 to 1580.
http://www.gutenberg.net/etext/10625

The Jargon Database

A repository of popular neologisms, management speak, and technical terms relevant to various regions, jobs, and cultures, and organized by categories.
http://www.jargondatabase.com

English-dictionary.us

Fast no-frills English dictionary.
http://www.english-dictionary.us

Collins Word Exchange

Dictionary searches a variety of word and phrase resources, including the Collins English Dictionary, texting abbreviations, internet links, and words submitted by users.
http://www.collins.co.uk/wordexchange/

Elizabethan Dictionary

Provides the origins and meanings of Elizabethan words and vocabulary including obscure Shakespearean expressions.
http://www.william-shakespeare.info/william-shakespeare-dictionary.htm

What Does That Mean

A free lexicon of English idioms, words, and catch phrases from around the world.
http://www.whatdoesthatmean.com/index.php/Main_Page