AllWords.com
Features two modern English dictionaries, multilingual search, and translation. Also features a guide to language sites on the web and a language discussion forum.
http://www.allwords.com/

Cambridge International Dictionaries
Free online dictionary from Cambridge University Press.
http://dictionary.cambridge.org/

Campus Program: Language Dictionaries
A compilation of a large number of dictionary websites grouped by language.
http://campusprogram.com/research/dictionaries/language/

Cooldictionary.com
Free edition of a complete Webster dictionary. Fully crosslinked.
http://www.cooldictionary.com/

Dictionaries on the Web
Link collection -- over 100 links to various dictionaries of about 40 languages.
http://www.helsinki.fi/~hkantola/dict.html

Dictionaries, Lexica and Lexical Resources
Collection of links to various online dictionaries and other lexical references.
http://www.sil.org/linguistics/etext.html#dictionaries

Dictionarium
Directory of English and foreign-language dictionaries.
http://www.dictionarium.com/

Dictionary Building Software for Reporters
Software program for realtime reporters and captioners that lists many diverse vocabulary lists.
http://www.dictionaryjumpstart.com/

Dictionary of Comprehension
A Dictionary of Comprehension in different languages.
http://www.dictionarydictionary.com/

Dictionary of Difficult Words
Search or browse this dictionary of more than 13,000 words.
http://www.tiscali.co.uk/reference/dictionaries/difficultwords/

Dictionary Society of North America
An international organization of librarians, booksellers, translators, linguists, publishers, writers, journalists, and collectors. Founded in 1975 to further research in dictionary making, study, collection, and use. Member of the American Council of Learned Societies.
http://polyglot.lss.wisc.edu/dsna/index.html

Dictionary.com
Free online dictionary search, translator, word of the day, crossword puzzles and word games, and vocabulary learning resources for many languages.
http://dictionary.reference.com/

Dictsearch
Search a variety of dictionaries including monolingual, bilingual, and specialty dictionaries.
http://www.foreignword.com/Tools/dictsrch.htm

eLook Dictionary
Provides definitions, synonyms, and related words.
http://www.elook.org/dictionary/

EZresearch.com
Provides a directory of dictionaries.
http://www.ezresearch.com/reference/dict.html

Free Dictionary and Free Translation
Collection of free dictionaries and translation sites. Supports searching all dictionaries with just one mouse click.
http://www.stars21.com/freemorn/index.html

Glossaries
Collection of more than 2400 links to glossaries and dictionaries.
http://frankdietz.com/glossary.htm

Glossaries by Language
Directory of multilingual dictionaries and dictionaries on specific subjects, alphabetized by language.
http://www.lai.com/glossaries.html

HyperDictionary.com
Includes a thesaurus and searchable dictionaries for English, computers, dreams and medicine.
http://www.hyperdictionary.com/

Hypertext Webster Gateway
WWW interface to multiple English dictionaries.
http://www.bennetyee.org/http_webster.cgi

KnowPlay?
Simple and integrated access to dictionaries, thesauri, encylopedias, and quotation databases.
http://www.kplay.cc/reference.html

Lexicool
Searchable directory of bilingual and multilingual dictionaries.
http://www.lexicool.com/

Merriam-Webster OnLine

http://www.m-w.com/

On-Line Dictionaries
Online specialty dictionaries for English, Russian, German, Finnish and Latin.
http://www.ets.ru/udict-e.htm

OneLook Dictionaries

http://www.onelook.com/

Online Dictionaries, Translators and References
Online dictionaries, translators, references accessible from a small pop-window. Requires use of a browser with Java script enabled.
http://www.esldesk.com/dictionaries/index.htm

Planet Translation
Directory of dictionaries, including unilingual, multilingual, and topical resources.
http://planettranslation.com/

Quotations: The Yale Dictionary
Project to create a searchable online database and a quotation dictionary from Yale University Press.
http://yalepress.yale.edu/yupbooks/qyd/

Research-It
Includes several dictionaries and a thesaurus as well as online tools for shipping and mailing, currency exchange, and language translation.
http://www.itools.com/

Strange Dictionaries
Free online versions of the Dictionary of One-Letter Words, the Dictionary of All-Vowel Words, the Dictionary of All-Consonant Words, and other strange dictionary resources.
http://www.blueray.com/dictionary/

The Alternative Dictionaries
Includes a list of slang terms and phrases in various languages.
http://www.alternative-dictionaries.net/

The Century Dictionary Online
Free 500,000 word dictionary of English with an encyclopedia and world atlas. Uses DjVu and JPEG formats to display page images. Has headword lookup and full text search of 22 million words of underlying text.
http://www.global-language.com/CENTURY/

The Glossarist
Searchable directory of glossaries and topical dictionaries containing terms and definitions on hundreds of subjects.
http://www.glossarist.com/

The Newbury House Online Dictionary
Search over 40,000 entries to get clear concise definitions and when available related pictures.
http://nhd.heinle.com/

The Online Dictionary List
A large directory of online dictionaries, both in English and bilingual, including specialist dictionaries.
http://www.clearenglish.net/dictionary.htm

Voycabulary
Online dictionary and thesaurus web linking lookup reference tool.
http://www.voycabulary.com/

Web Dictionaries
Multi-search tool by Tinh Van, which consults English-only dictionaries, and Vietnamese into English or French translation dictionaries.
http://www.tinhvan.com/scripts/tvis/webdict/webdict.pl

Word Spy
Site dedicated to recently coined words and existing words revived into modern usage.
http://www.wordspy.com/

WordWeb
A free English thesaurus and dictionary for Windows.
http://wordweb.info/free/

yourDictionary.com
An index of on-line dictionaries in over 200 different languages. Includes an index of on-line grammars, word of the day by email, and several pages of linguistic fun.
http://www.yourdictionary.com/