Dictionaries & Thesaurus (Online)

http://www.ldoceonline.com/  << Longman Dictionary of Contemporary English Online (Free)

http://www.dictionary.com

http://www.bartleby.com/61/    <<  The American Heritage® Dictionary of the English Language

http://www.bartleby.com/62/  << Roget’s II: The New Thesaurus

http://www.askoxford.com/    << Oxford Online Dictionary