Merriam-Webster is a very complete site that provides a free online dictionary, thesaurus, audio pronunciations, Word of the Day, word games, and other English language resources. It is aimed at publishing language-related reference works.
It also publishes a wide selection of print and electronic products such as Merriam-Webster’s Collegiate Dictionary, Eleventh Edition—America’s best-selling desk dictionary—and Webster’s Third New International Dictionary, Unabridged. Useful and handy, this site also offers services like English- Spanish dictionary, Medical dictionary and a Merriam-Webster online store where you can download comprehensive resources of the English language and much more. Take a look at it. Will definitely be of your help. 
