i need a dictionary english-english How is it Urban dictionary?
urbandictionary.com can be useful for words that aren't listed in mainstream dictionaries -- especially slang words, words used by small minority groups, and words that were invented very recently. However, it isn't professionally produced and is no good as a general-purpose dictionary.

I find http://www.onelook.com useful. It gives you links to many online dictionaries. Individual good-quality dictionaries are at:


http://www.askoxford.com (search box at top left; choose "English dictionary")
Students: Are you brave enough to let our tutors analyse your pronunciation?
I'm a fan of Merriam-Webster - it's bookmarked on my computer and I use it daily.

Please do NOT use Urban Dictionary as your primary source of information. Any idiot can add words and meanings with out any sort of peer review, and many idiots do exactly that.

With the real dictionaries cited by Mr. Wordy, there is a strict review process to confirm that usage reflects current standard English.
Mr Wordy
http://www.askoxford.com (search box at top left; choose "English dictionary")

That should, of course, be "top right".