If you are looking for an efficient dictionary which will help you to translate you have to test the WordReference web application. With it you will be able to translate between 15 different languages as well as finding different tools wiht a great linguistic tool.
For each language you will find a dictionary which will allow you to translate it to and from English, as well as to other languages like French, Portugese and German in certain cases. You will also be able to find the verb conjugation, definition and synonyms.
When you are looking for a word in WordReference it will show you all kinds of different meanings for it as well as offering the possibility to search in specific vocabulary dictionaries. It also shows the most usual sentences in that language with the word, related terminology and forums.
The fact that it uses the dictionaries by such prestigious publishers as Oxford and Collins as an information source make WordReference one of the most reliable and efficient linguistic resources which you will be able to find over Internet.
If you need to resort to a dictionary don't think about it twice and check WordReference to solve all your linguistic doubts.