American Heritage Dictionary

 Over 200,000 entries feature 10,000 new words and senses, 70,000 audio word pronunciations, 900 full-page color illustrations, language notes and word-root appendixes

A Dictionary of Units and Measures

 describes the relationship between various English and metric units

A Maths Dictionary for Kids

 animated, interactive dictionary for students which explains over 500 math terms in simple language

Internet Picture Dictionary

dictionary shows words and pictures

Little Explorers Picture Dictionary

 2,406 illustrated dictionary entries! Each word is used in a meaningful example sentence. Most entries have links to a related web site. Just click on an underlined word (or its accompanying picture), and you'll link to a related page

Net Dictionary

 Netdictionary is an alphabetical reference guide to technical, cultural, and humorous terms related to the Internet

Word Central

 look up words, build your own dictionary, and do Daily Buzzword