Ready Reference
Dictionaries
allwords.com
http://www.allwords.com/
A dictionary with all definitions in English, but the ability to search for a word in English, French, German, Dutch, Italian, and Spanish. Additionally, there is a pronunciation file for each English word.
The American Heritage Dictionary of the English Language
http://www.bartleby.com/61/
Online version of the 1996 edition of the popular English language dictionary, featuring over 200,000 entries. Entries include pronunciation guide, definition, and brief etymology. Searchable only (no browsing).
Cambridge Dictionary of American English
http://dictionary.cambridge.org/
Students and scholars of American English can use this site to search the full text of the Cambridge Dictionary of American English. The dictionary gives full sentence examples of how words are used in American English, and explains thousands of American idioms.
Dictionary.com
http://www.dictionary.com/
Dictionary.com is the best general English-language dictionary online. Its simple search form hides a sophisticated multi-source search of Webster's Revised Unabridged Dictionary, WordNet, The Free Online Dictionary of Computing, Jargon File, The Elements, Easton's 1897 Bible Dictionary, Hitchcock's Bible Names Dictionary, U.S. Gazetteer, and the CIA World Factbook. Links on Dictionary.com's home page lead to thousands of other English dictionaries (including WWWebster Dictionary), jargon dictionaries, writers' dictionaries, non-English dictionaries, and other language resources.
Directory of Translation Dictionaries
http://www.lexicool.com
Lexicool.com's online dictionary directory currently has links to over 5000 bilingual and multilingual dictionaries and glossaries freely available on the Internet.
Encyberpedia Dictionary and Glossary
http://www.encyberpedia.com/glossary.htm
Complete listing of all the major dictionaries and glossaries on the Internet. Includes everything from sign language, telecommunications, computers, weather, tides, water quality and a lot more. Some annotations.
Hyperdictionary
http://www.hyperdictionary.com/index.html
This online dictionary provides word definitions from five separate resources: an English dictionary, a computer dictionary, a thesaurus, a dream dictionary and a medical dictionary.
Information Please Almanac
http://www.infoplease.com/dictionary.html
Online version of the popular almanac which you can browse by topic or search. Also includes the Random House Websters College Dictionary and the Columbia Encyclopedia.
Jargon File Resources
http://catb.org/%7Eesr/jargon/
"This page indexes all the WWW resources associated with the Jargon File and its print version, The New Hacker's Dictionary. It's as official as anything associated with the Jargon File gets." The Jargon File has been known as the lexicon of esoteric hackerly words and phrases since at least 1991. The site also includes the history and folklore of hackers. It has a searchable database for jargon terms and also has links to pages that have other versions of search engines to search the text. You can also download the entire text as a compressed gzip file.
Merriam-Webster's Collegiate Dictionary
http://www.m-w.com/netdict.htm
An excellent hyperlinked dictionary and thesaurus, based on the Merriam-Webster dictionary. The search engine supports wildcards and right-hand truncation. A help page and pronunciation guide are included.
Roget's Thesaurus
http://thesaurus.reference.com/
The Intenet edition of Roget's Thesaurus. Search for words or browse alphabetically and by word category.