學習英文好用字典（依推薦程度排序）

英漢字典

發音，用法，例句－n詞庫
http://www.nciku.com.tw/

金山詞霸

http://www.iciba.com/

林語堂當代漢英辭典
http://humanum.arts.cuhk.edu.hk/Lexis/Lindict/

有道海量辭典
http://dict.youdao.com/

線上英漢字典
http://cdict.net/

英英字典

口語字典

http://urbandictionary.com/

Longman dictionatry

http://www.ldoceonline.com/

Oxford Advanced Learner's Dictionary

http://www.oxfordadvancedlearnersdictionary.com

Onelook

http://www.onelook.com/

Dictionary and Thesaurus - Merriam-Webster Online
http://www.merriam-webster.com/

Cambridge Unversity Press
http://dictionary.cambridge.org/

片語字典

http://www.thefreedictionary.com/

multi dictionary sensagent.com
http://dictionary.sensagent.com/

同義字字典
http://freedictionary.org/
http://encarta.msn.com/encnet/features/dictionary/dictionaryresults.aspx?lextype=3
http://llohe-ocd.appspot.com/

例句字典
http://www.yourdictionary.com/

Webster's Online- with Multilingual Thesaurus Translation

http://www.websters-online-dictionary.org/