All Words.Com: English dictionary with multilingual search capability. The ALLwords.com site offers search results from two English dictionaries: the Concise Dictionary and The Random House Webster's Unabridged Dictionary. The results of a search appear separately.
WordReference.com: The Collins English Dictionary + four multilingual translation dictionaries. Uses the Collins Dictionaries from HarperCollins. Type in a word in the forms to the left for a quick definition. Contains four multilingual translation dictionaries and one extremely big English dictionary: Spanish English Dictionary, French English Dictionary, Italian English Dictionary, German English Dictionary, and The Collins English Dictionary.
YourDictionary.com: Dictionaries and Grammar Multilingual Service. Includes a talking dictionary. A language products and services company that maintains the most comprehensive and authoritative language portal on the web with more than 2500 dictionaries and grammars in over 300 languages, games that build language skills, and a forum (The Agora) for discussing language issues with the logophile community. More than 1,000,000 people a month visit our website. Free registration.