Many of u, like me may be wondering how to install offline dictionary in ubuntu.I have tried to search and found a very good one..u will definitely going to like it...the application's name is-- Stardict.

How to Install??

Use ubuntu software center or your terminal to install it.
sudo apt-get install stardict

After the installation, you have to add your favourite dictionary in stardict.For this follow these steps--

1. Download your dictionary from here--
(go here and click on the free dictionary link). i have downloaded babylon, you can download any of it.
2. There will be a lot of tarballs inside your selected options,you can download
one or many tarballs.
3. For every tarballs repeat these steps--
a) Extract it- tar -xjvf (name of your tarball)
b) Move it - mv (name of your extracted folder) /usr/share/stardict/dic

4. After these steps, open stardict(Applications->Accessories->Stardict) and
look for any word.