WordCentral.com
Merriam-Webster's site for kids has a student dictionary, Daily Buzzword, and interactive word games. Includes homework help and lesson plans for parents and teachers.

Wordsmyth
A dictionary and thesaurus in one. Also gives parts of speech and examples for more than 50,000 words.

Little Explorers
Picture dictionary gives definitions, pictures, and Internet links for over 2,350 entries. Includes translations for English to and from Dutch, French, Spanish, and more.

The American Heritage Dictionary of the English Language
Contains over 90,000 entries, including 70,000 audio word pronunciations.

Biographical Dictionary
Read about more than 28,000 notable men and women from history. Search by names, dates, professions, achievements, and more.

Webopedia
Definitions of many computer-related terms, from hardware to the internet.

The Skeptic's Dictionary
Definitions and essays on occult, paranormal, and supernatural ideas and practices from the point of view of someone who is a sceptic, that is, does not believe in these things.

DinoDictionary.com
Features profiles of over 300 known dinosaurs along with pronunciations of their names.

ArtLex
Dictionary of visual art defines more than 3,500 art-related terms. Also includes a comprehensive collection of artwork and famous quotes.

Fact Monster
An online dictionary with definitions of over 125,000 words.

PSEUDOdictionary
Defines everyday words including slang, webspeak, and colloquialisms.

Free On-line Dictionary of Computing
A searchable dictionary of terms from computing and related fields.

The Internet Picture Dictionary
Free, online multilingual picture dictionary with interactive activities for English, French, German, Spanish, Italian and ESL learners.

Dictionary.com
Online English dictionary, thesaurus and reference guide. Includes word games, online translator, and word of the day feature.

Realdictionary.com
Features search to locate words by initial letters and numbers.

RhymeZone
Online rhyming dictionary. Search for a word and get a list of potential words that rhyme in addition to a definition.

OneLook Dictionary Search
Type in a word and search many dictionaries at once. Also has a reverse dictionary.

Terminology Collection: Online Dictionaries
Glossaries for several languages and for specialized fields from the University of Vaasa, Finland.

NetLingo Dictionary
Provides a glossary of Internet jargon and acronyms.

wordIQ
Search on several different dictionaries, an encyclopedia, and the web.

Ice Phoenix Vocab Project
Downloadable program that looks up entire lists of vocabulary words.

MSN Encarta Dictionary
Online dictionary with over 100,000 entries, definitions, and pronunciations.

Giant Picture Dictionary
Free online picture dictionary. Includes pictures representing both concrete and abstract concepts.