Merriam-Webster

No other dictionary matches M-W’s accuracy and scholarship in defining word meanings. Our pronunciation help, synonyms, usage and grammar tips set the standard.

Apertium

To see the whole list of general documentation pages written in English, see documentation in English. Pour ceux qui sont plus à l’aise avec la langue française, une partie des pages anglaises a été traduite.

Apple Dictionary

Your Mac also comes with a versatile Dictionary application.

Longman English Dictionary Online

The Longman Dictionary of Contemporary English Online is an online version of the CD-ROM of the…

Oxford Dictionaries

Free online dictionary of British English and American English from Oxford.

The Free Dictionary

The World’s most comprehensive free online dictionary, thesaurus, and encyclopedia with synonyms, definitions, idioms, abbreviations, and medical, financial, legal specialized dictionaries

WordWeb

One-click lookup in any almost any Windows program; Hundreds of thousands of definitions and synonyms; The latest international English words; Works offline, or reference to Wikipedia and web references.