The mLexicon is the best multilingual English dictionary for Mac. It works offline so it is ideal for your business trip or vacation. It helps you easily find the translation of English words in five other languages: German, Italian, French, Finnish and Spanish.
The application is not intended for translation of sentences however you can use built-in integration with the Bing Translator service for this purpose. This feature, however, requires an internet connection. All searched results can be stored for later off-line use.
Please visit accompanying web site to see the application in action: www.mlexicon.com