No you don’t need to use:

cd home/directoryA/directoryB/directoryC/DirectoryD
./somefile 

You can simply run the command by prefixing it with its path:

/home/directoryA/directoryB/directoryC/DirectoryD/somefile

Because you are already in the /home/directoryA you can use the current directory shortcut . and run the command like this:

./directoryB/directoryC/DirectoryD/somefile

I noticed OP has expanded scope via comments under other answers. Here is some additional information:

To find out where somefile is located use: locate somefile.
If somefile was added today you need to first update the locate database by running sudo updatedb.
When there are multiple versions of somefile located in the PATH you can find out which one is executed first use which somefile.
If you want to run somefile without specifying a directory name in front put it in the path. To check the path use echo $PATH. Common path locations to put somefile are /usr/local/bin (if it uses sudo powers) and /home/your_user_name/bin (you might have to create the directory first).
You can also add /home/directoryA/directoryB/directoryC/DirectoryD/ to your path but that would be highly unusual. However you could then simply type somefile no matter what directory you are in and it will run.
Of course somefile must be executable which you set with the command: chmod a+x /home/directoryA/directoryB/directoryC/DirectoryD/somefile