If you want to install any package name in your system but know only the starting of the package name, you can do this :
Open you command prompt [Ctrl] + [Alt] + [T] . Type in the first few letters of the package name that you want to know and hit [Tab] twice
This will give you the list of packages that start with those letters. For example, if you type fi
and hit [Tab] twice. you will get all the package names that start with fi
In case you know only the name of the software and not the beginning of the package name, you can browse through the package list in this page - List of packages in any version of Ubuntu
Hope this helped.
See attached image!
Also read The two ways to install VLC media player in Ubuntu 11.10 - Simple steps