As you already know "idiom" means  a group of words used together with a meaning that you cannot guess from the meanings of the separate words.

      Idioms are so fun to use. We should use idioms more to make our speech more attractive and impressive. It's a way to make your language more vivid and interesting!!

Here are two idiom dictionaries that you can use.

Here is a free online Talking Dictionary of English Pronunciation!!

Click on it;

http://www.howjsay.com/

Here are the dictionary links you can always use :)

http://dictionary.cambridge.org/

http://thesaurus.com/

 

 http://oxforddictionaries.com/