Cambridge Dictionaries OnlineCambridge University Press has been publishing dictionaries for learners of English since 1995. Cambridge Dictionaries Online began offering these dictionaries completely free of charge in 1999 — and today, Cambridge Dictionary is still growing.
Dictionary.comDictionary.com is the world's leading digital dictionary. They provide millions of English definitions, spellings, audio pronunciations, example sentences, and word origins.
Merriam-Webster Online DictionaryThe Merriam-Webster Online Dictionary is based on the print version of Merriam-Webster's Collegiate® Dictionary, Eleventh Edition. The online dictionary includes the main A-Z listing of the Collegiate Dictionary, as well as the Abbreviations, Foreign Words and Phrases, Biographical Names, and Geographical Names sections of that book.