Word Assault
Looks up multiple words simultaneously using several databases including Webster's, Easton's, Wordnet, and the Devil's Dictionary.
http://www.wordassault.com/

Word Central
Student dictionary and rhyming dictionary online at Merriam-Webster's website. Daily Buzzword by subscription.
http://www.wordcentral.com/

OneLook Dictionaries
Look up a word or term in an Internet dictionary or glossary. Free search access to a frequently updated database of words, terms, names, and acronyms.
http://www.onelook.com/

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

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/

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

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

Skeptic's Dictionary
Skeptical definitions and essays on occult, paranormal, supernatural and pseudoscientific ideas and practices with references to the best skeptical literature.
http://skepdic.com/

Information Please Dictionary
Infoplease's free online dictionary. Features almanacs, an encyclopedia, and an atlas.
http://www.infoplease.com/dictionary.html

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

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/

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

The Alternative Dictionaries
Includes a list of slang terms and phrases in various languages.
http://www.notam02.no/~hcholm/altlang/

Lighting Design Terminology
Explanations of terms used in architectural lighting and lighting simulation.
http://www.schorsch.com/kbase/glossary/

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

DICT Development Group
A WWW interface to several freely available on-line dictionaries, including Webster's 1913, the Jargon File, the US Gazetteer, and Easton's Bible Dictionary.
http://www.dict.org/

The Newbury House Online Dictionary
Search over 40,000 entries to get clear concise definitions and when available related pictures.
http://nhd.heinle.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 Superhero Dictionary
Each entry compares a superhero's name with its real life meaning and includes comparison pictures and pronunciations.
http://shdictionary.tripod.com/

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

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

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

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

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

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/

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

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

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

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/

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

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

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/

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

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

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

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

Oxford Advanced Learner's Dictionary
Allows users to search, free of charge, for entries in the latest (year 2000) edition of the Oxford Advanced Learner's Dictionary.
http://www.oup.com/elt/oald/

Merriam-Webster OnLine
A free, searchable on-line dictionary and thesaurus, word games, a word of the day, and many other English language and vocabulary reference tools and resources.
http://www.m-w.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

Dictionary Link
A directory of free online language resources such as dictionaries, thesauruses, language translators, and encyclopedias.
http://www.dictionarylink.com/

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

Webster's Online Dictionary: The Rosetta Edition
This database doubled with a metasearch tool extracts records from a variety of online and public-domain paper dictionaries, both general and specialized. It offers English definitions, as well as translations from/to a hundred languages.
http://www.websters-online-dictionary.com

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

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/

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

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

Inter Active Terminology for Europe (IATE)
The European Commission's multilingual term bank. Particularly rich in technical and specialized terminology related to European Union policy.
http://iate.europa.eu/iatediff/