Dictionaries

WordCentral.com :

 
[ Kids/Teens ] - Merriam-Webster's site for kids has a student dictionary, Daily Buzzword, and interactive word games. Includes homework help and lesson plans for teachers.
Alcwin.org :

[ Mature Teens ] - Site listing several types of dictionaries related to the sciences.
The American Heritage Dictionary of the English Language :

[ Kids/Teens/Mature Teens ] - Contains over 90,000 entries, including 70,000 audio word pronunciations.
ArtLex :

[ Teens/Mature Teens ] - Dictionary of visual art defines more than 3,500 art-related terms. Also includes a comprehensive collection of artwork and famous quotes.
Biographical Dictionary :

[ Kids/Teens/Mature Teens ] - Read about more than 28,000 notable men and women from history. Search by names, dates, professions, achievements, and more.
Dictionary.com :

[ Kids/Teens/Mature Teens ] - Online English dictionary, thesaurus and reference guide. Includes word games, online translator, and word of the day feature.
DinoDictionary.com :

[ Kids/Teens/Mature Teens ] - Features profiles of over 300 known dinosaurs along with pronunciations of their names.
eLook Dictionary :

[ Kids/Teens ] - Provides definitions, synonyms, and related words.
Fact Monster :

[ Teens/Mature Teens ] - An online dictionary with definitions of more than 125,000 words and links to other related student tools.
Free On-line Dictionary of Computing :

[ Kids/Teens/Mature Teens ] - A searchable dictionary of terms from computing and related fields.
Giraffian Children's Picture Dictionary :

[ Kids ] - A collection of illustrated words and concepts, aimed at children in preschool or early primary years.
Ice Phoenix Vocab Project :

[ Teens/Mature Teens ] - Downloadable program that looks up entire lists of vocabulary words.
InfoVisual :

[ Kids/Teens/Mature Teens ] - Thematic visual dictionary that focuses on learning through images. Concise definitions within the fields of vegetal biology, animal biology, human anatomy, and transportation.
The Internet Picture Dictionary :

[ Kids/Teens/Mature Teens ] - Free, online multilingual picture dictionary with interactive activities for English, French, German, Spanish, Italian and ESL learners.
Little Explorers :

[ Kids ] - 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.
NetLingo Dictionary :

[ Teens/Mature Teens ] - Provides a glossary of Internet jargon and acronyms.
OneLook Dictionary Search :

[ Kids/Teens/Mature Teens ] - Type in a word and search many dictionaries at once. Also has a reverse dictionary and translations.
Pidic.com :

[ Teens/Mature Teens ] - An online picture dictionary with thousands of images
PSEUDOdictionary :

[ Mature Teens ] - Defines everyday words including slang, webspeak, and colloquialisms.
RhymeZone :

[ Kids/Teens/Mature Teens ] - Online rhyming dictionary. Search for a word and get a list of potential words that rhyme in addition to a definition.
The Skeptic's Dictionary :

[ Teens/Mature Teens ] - 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.
Tech Terms Computer Dictionary :

[ Mature Teens ] - A searchable dictionary of computer terms with definitions explained in simple language.
Terminology Collection: Online Dictionaries :

[ Teens/Mature Teens ] - Glossaries for several languages and for specialized fields from the University of Vaasa, Finland.
WebDictionary.co.uk :

[ Teens/Mature Teens ] - Online dictionary and reference website.
Webopedia :

[ Teens/Mature Teens ] - Definitions of many computer-related terms, from hardware to the internet.
wordIQ :

[ Teens/Mature Teens ] - Search on several different dictionaries, an encyclopedia, and the web.
Wordsmyth :

[ Kids/Teens/Mature Teens ] - A dictionary and thesaurus in one. Also gives parts of speech and examples for more than 50,000 words.