First of all I like to say the name of Babiloo. It is available on 'Ubuntu Software Center'. You need to use dict files for work with it. Get many dictionary from this website.
It is a cross-platform open source thesaurus based on WordNet. Arthe is really handy & light, easy to use for every user. It is available at 'Ubuntu Software Center'
It is a default dictionary on Ubuntu. Normally it use online to search definition of a word. You can make it work offline. It is also available on 'Ubuntu Software Center'. Search for 'dictd'. You will get many files to download. Choose very carefully.
dictd will install dict, dict-wn, dict-gcide, dict-jargon, dict-folder. You can install a thesaurus. Choose dict-moby-thesaurus to install via 'USC'
Now time to configure it to work offline. Go to Edt> Preference and click on Source. Add a new source as below.
Discription: Local ServerYou have done configuring it. Now search any word and you will feel the speed.
Transport: Dictionary Server