RhymeBook - RhymeBook is one of the best application that helps its users to find out the whole rhyme if they know some words of rhyme.
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
Collins English Dictionary - The official Collins English Dictionary online.
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.
Urban Dictionary - Urban Dictionary is a Web-based dictionary of slang words and phrases.