@sulin,
What if, after reading a word and looking it up in the dictionary, you could see all the other words with similar meanings? What if you could find out instantly which words are formal and which are used in everyday speech? What if you could find out which ones are BrE and which NaE?
There is such a "dictionary", Sulin, but it's called an Activator. It focuses on the words/the idioms that are the hardest to understand for EFLs and the real neat part of this is that it puts them under one simple keyword. Within that keyword there could be 15 or 20 subheadings that describe nuances for those words
Here's a link to the book,
http://www.amazon.com/s/ref=nb_sb_noss?url=search-alias%3Dstripbooks&field-keywords=longman+language+activator&x=0&y=0
You can probably find a copy of this book in a public library.