- Acronym Finder
- American Heritage Dictionary of the English Language
- Dictionary.com
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Forvo
- Word pronunciation dictionary, with words pronounced by native speakers.
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The Free Dictionary
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- Merriam-Webster's Collegiate Dictionary
- Merriam-Webster Visual Dictionary Online
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Memidex
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Online Etymology Dictionary
- Dictionary of word orgins and histories.
- Oxford Dictionaries Online
- Wiktionary
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Wordnik
- "An online community of word lovers."
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WordSpy
- Words not yet found in the dictionary.