Here is a quick list for the links of English online dictionaries.

www.dictionary.cambridge.org

www.ldoceonline.com

www.merriam-webster.com

www.oxforddictionaries.com

www.thefreedictionary.com

http://www.englishpage.com/dictionaries/english_dictionary.html

http://www.onelook.com/

http://www.alphadictionary.com/index.shtml

http://lookwayup.com/free/

http://thesaurus.com/

http://www.macmillandictionary.com/

http://oald8.oxfordlearnersdictionaries.com/

http://dictionary.reference.com/

http://lookwayup.com/free/

If you can give us any additional link of any English online dictionary please add it as a comment to this page.