Dictionary.com Unabridged
Based on the Random House Dictionary, © Random House, Inc. 2012.
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Online Etymology Dictionary, © 2010 Douglas Harper
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The American Heritage® Stedman's Medical Dictionary
Copyright © 2002, 2001, 1995 by Houghton Mifflin Company. Published by Houghton Mifflin Company.
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The American Heritage® Science Dictionary
Copyright © 2002. Published by Houghton Mifflin. All rights reserved.
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The Free On-line Dictionary of Computing, © Denis Howe 2010 http://foldoc.org
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Encyclopedia Britannica, 2008. Encyclopedia Britannica Online.
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