Bitdefender for Ubuntu

There are so many third party anti-virus applications to Ubuntu. One of the best anti-virus application is Bitdefender. Check Bitdefender for more information.
Bit defender is one of the efficient and effective virus scanner for operating systems like Ubuntu. For home/personal use you can get one year free license, whereby it is possible to update freely for one year. For free license refer here. Just go to the site and register to get one year free license.

Installation:
there are two types of installations one is from the terminal (hassle free); and the other is manual i.e., from the Bitdefender website; go to the Bitdefender portal and download .DEB file from Bitdefender for Unices, just install it by Debian Package manager.

And from the terminal,
first; go to System > Administration > Software Sources; there under other software (second button) add the following line;

deb http://download.bitdefender.com/repos/deb/ bitdefender non-free

then reload software sources; after update there will be a message, don't worry.
go to terminal; Applications > Accessories > terminal; and then type or paste the following lines, to add gpg key;

wget http://download.bitdefender.com/repos/deb/bd.key.asc
sudo apt-key add bd.key.asc

then, again update (but this time from the command-line, by typing or pasting following line;
sudo apt-get update

after the update, type the following command-line;
sudo apt-get install bitdefender-scanner-gui

that's all it will install two files namely; bitdefender-scanner bitdefender-scanner-gui; the file size will be some where around 35MB.

Offline dictioneries in Ubuntu

Unfortunately by default Ubuntu comes with On-line dictionaries. But there is every possibility for either installing off-line dictionaries or making the local dictionaries working off-line.

One of the best efforts to install Off-line dictionary is installing artha. It is basically an Off-line thesaurus based on Wordnet.
just simply type the following line in terminal:

sudo apt-get install artha

the beauty of this is that you can select any word on your desktop and simply press ctl+alt+w thats all artha pop up and gives you required meaning with other stuff.

But, for those who have emotional attachment towards GNOME, you can configure Dictionary server.
the following is the way to installing local dictionary server, with required dictionaries and thesaurus;

sudo apt-get install dictd dictzip dict-wn dict-foldoc dict-jargon dict-gcide dict-moby-thesaurus

and configure the Dictionary in following way;

go to ............ Applications > Office > Dictionary > Edit > Preferences

add a new source using 127.0.0.1 as Hostname and select it as your default source