1. Great monolingual dictionary with pronunciation.

www.macmillandictionary.com

 

2. Dictionary as well as articles,trending words,videos and blogs.

www.oxforddictionaries.com

 

 

3. Synonyms,antonyms, Word of the day.

www.thesaurus.com

 

 

4. Synonyms,antonyms, Word of the day. Click on ´words and language´for interesting articles: longest words,commonly confused words,etc.

www.collinsdictionary.com

 

 

5. Click on ´features´and ´The English we Speak´for new words.

www.bbc.co.uk/learningenglish

 

6. Idioms for every letter of the alphabet! Phrasal Verbs quizzes,etc

www.usingenglish.com