Universal Lookup and Word Translations

Anywhere in the O/S you can ctrl-right-click on a word and a popup is displayed that gives you a definition, synonyms, antonyms, and translations that you have subscribed to. It can also pronounce the word. It's not my idea. In Windows there is a commercial application called Babylon that does this.
2 things are required
1. There are already many free translation dictionaries and thesauruses (thesauri?) but they need to be brought together into a standard that can be subscribed to. You could subscribe to online and local downloaded dictionaries.
2. A small desktop application that will take the word being clicked and look it up and display the result.

In Windows I used to used Babylon and I can attest that a program with this kind of functionality adds incredibly to efficiency of desktop users.