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. http://www.pdictionary.com/

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. http://www.skepdic.com/

WebDictionary.co.uk [ Teens/Mature Teens ] - Online dictionary and reference website. http://www.webdictionary.co.uk

Webopedia [ Teens/Mature Teens ] - Definitions of many computer-related terms, from hardware to the internet. http://www.webopedia.com/

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 parents and teachers. http://www.wordcentral.com/

wordIQ [ Teens/Mature Teens ] - Search on several different dictionaries, an encyclopedia, and the web. http://www.wordIQ.com

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