Dictionaries

General works containing alphabetical lists, with information given for each term.

Sub-headings:

English

In addition to regular online dictionaries, these English language sites include dictionaries dealing with rhyming, slang, and sign language.

Non-English

Dictionaries for languages other than English.

Translation Dictionaries

Dictionaries that, given a word in one language, will show the identical or related word in another language.

Glossaries

Resources in this category:

Acronym Finder
http://www.acronymfinder.com/

Provides more than 750,000 definitions for acronyms, initialisms, and abbreviations. Search by abbreviation or word abbreviated, or browse by subject category.

AskOxford.com: Free online dictionary resources from Oxford University Press
http://www.askoxford.com/

Provides essays, definitions, resources, FAQs, and games about the English language, usage, history, grammar, and related topics. If your questions are not answered on the website, you can send them to the Oxford Word and Language service team.

The DICT Development Group
http://www.dict.org/bin/Dict

A dictionary search tool that allows natural language searching for definitions from multiple dictionaries.

The Free Dictionary
http://www.thefreedictionary.com/

This website provides access to English, Spanish, German, French, Italian, Chinese, Portuguese, Dutch, Norwegian, Greek, and Russian dictionaries; English-language Medical, Legal, and Financial dictionaries; a Thesaurus, Encyclopedia, and other language resources.

Idiom Site
http://www.idiomsite.com/

Are you having a "bad hair day"? Or do you know someone who is "not playing with a full deck"? Find the meanings and origins of common idioms on this site.

Medi-Lexicon
http://www.medilexicon.com/

Dictionaries of medical, pharmaceutical, biomedial, and healthcare terms, abbreviations and acronyms, as well as other health-related resources.

Merriam-Webster Visual Dictionary Online
http://visual.merriam-webster.com/

A dictionary that uses images to define words. Words are sorted into themes; by clicking on images you can find words and definitions.

NetLingo: The Internet Language Dictionary
http://www.netlingo.com/

A dictionary of new technology-related words, phrases, and abbreviations. Includes news and a word of the day.

Resources for East Asian Language and Thought
http://www.acmuller.net/

Indexes, dictionaries, bibliographies and electronic texts on East Asian religion and philosophy. Includes a "Digital Dictionary of Buddhism", indexes to several biographical works on Korean and Japanese Buddhists, translations of classical religious and philosophical texts, and links to many other resources.

SYMBOLS.com -- Online Encyclopedia of Western Signs and Ideograms
http://www.symbols.com/

"The world's largest on-line encyclopedia of graphic symbols." Search by symbol shape and components or by word. The symbols range from historical to contemporary, and are supplemented by articles about their history, use, and meaning.

Techterms.org: Computer and Technology Defined and Explained
http://www.techterms.com/

"The Tech Terms Dictionary is a constantly growing collection of computer and technology terms. Each definition is written in a way that is easy for the reader to understand and serves to explain the term, not just define it."

VoyCabulary
http://www.voycabulary.com/

"VoyCabulary is a powerful web tool which will link web pages or phrases to online references like dictionaries or thesauruses -- This provides a convenient and speedy way to lookup words quickly and efficiently, without disrupting your normal web browsing... If you don't want to process a webpage, but have some text (maybe from a word processor), you may simply cut and paste it into the textbox and VoyCabulary will process it as well." Voycabulary includes an English Dictionary/Thesaurus as well as Medical, Acronym, and Computer dictionaries. Translations are available to and from English to Spanish, German, French, Japanese, Dutch, Swedish, Portuguese, Russian, Hungarian, and Welsh.

Wolfram|Alpha
http://www.wolframalpha.com/

Wolfram Alpha quickly locates facts, graphs, definitions, tables, numbers, formulas, and other data. Use the "Examples" page to browse and see all the different topics covered.

Wordnik
http://www.wordnik.com/

Provides information about words, where they come from, what they mean, how to pronounce them, related words, examples, statistics, images from Flickr, and even how they were used in Twitter.