Big Huge Thesaurus
Synonyms, antonyms, and rhymes (oh my!)
(Also blog post ideas and story plot/logline resources for writers.)
This site is based on source data from the Princeton University WordNet database, the Carnegie Mellon Pronouncing Dictionary, and suggestions from thousands of people on the internet just like you.
Good readability: Clear big text
Askdefine.com is an online dictionary for looking up English words. It has many features such as Auto completion when searching for words.
Multi source lookups of words. Some which are user driven and frequently updated. Translations of words from English to German, Spanish, French and many more languages.
List of words that rhyme with a given word.
A synonyms dictionary and antonyms