Online Dictionaries and Encyclopedias

Acronyms and Abbreviations Database, Searchable
Acronym Finder - not only looks up acronyms in a database of about 60,000, but allows you to search words through the acronyms' meanings.
ARTFL Project: French-English Dictionary Form
Assorted Encyclopedias on the Web - arranged by topic, this gets you to encyclopedias of chess, cell biology, cosmology, herbs, and lots more.
Behind the Name - Their meanings and origins.
Catholic Encyclopedia - the 1913 edition. Still under construction, but a couple of hundred articles are in place.
Classical Dictionary - explains terms from classical mythology and art.
Dictionary - a dictionary, and thesaurus.
Dictionary of Phrase and Fable - complete text of the classic work.
Directory of Bilingual and Multilingual Dictionaries
Easton's BIBLE Dictionary
Encarta Concise Encyclopedia - and it's free, though the site also links to some of Bill Gates' fee-based services.
Encyclopedia.Com -A free service from the not-free Electric Library. The 17,000 some articles from the Concise Columbia Electronic Encyclopedia, Third Edition have hyperlinks to related articles as well as references to articles within the Electric Library database.
Encyclopedia of Psychology - over 2000 links from people & history to careers to theories and much more. From Jacksonville State University.
Encyclopedias Online -Yahoo's index.
Economics Dictionaries
FOLDOC-The Free Online Dictionary of Computing - over 12,000 extensively hyperlinked terms in computer science.
Foreign Language for Travelers - pick your language, and choose from complexes of travel-related words, such as directional words, time and date words, dining and shopping words. Click on sound file for pronunciation. With links to relevant dictionaries on the web.
Foreignword.com - contains an online dictionary search for 58 different languages
Internet Country Codes - what the 2-letter country codes in domain names refer to.
Internet Movie Database - if you didn't find it in the All-Movie Guide, try here. Both databases give very complete information for every film they list, who played what roles, producer, director, date, etc.
Lectric Law Lexicon - Legal dictionary and reference room
Musical Heritage Network Instrument Encyclopedia -For each instrument, the encyclopedia offers history, design information, and bibliography, along with brief discussions of musical works featuring them.
New Words in English
North American Industry Classification System (NAICS) - replaces the old Standard Industrial Classification System (SICS)
OneLook Dictionary - type in the word you want, and search simultaneous through 29 general or specialized dictionaries.
Online Medical Dictionary
Open Dictionary - Multilingual dictionary in some language, with meanings, etymologies and pronunciations with the aid of the Wiktionary project.
Oxymoron List
PC Webopedia
Semantic Rhyming Dictionary - insert word, ask for your choice of perfect rhyme, last sound only, homophones, synonyms; free, courtesy of Doug Beeferman at Carnegie-Mellon.
Slang Dictionary
Thesaurus
Universal Currency Converter
Web Exhibits - great images and analysis, academically oriented. It covers Art and Humanities, Social Sciences, Math, Computer Science, Life and Physical Sciences.
Webopedia - The only online dictionary and search engine you need for computer and Internet technology definitions.
Words of Art--a Glossary of Critical Terms
Wordsmyth English Dictionary-Thesaurus - This is also a dictionary of synonyms.
Yahoo Index to Dictionaries - all types of dictionaries, including different languages.
Your Dictionary - There are dictionaries for over 200 languages, plus for 78 topics including literature, linguistics, rhetoric, publishing, theater, metallurgy, finance, and geology to name a few.