Synfig is an open-source animation editing software that is free to download.

Assuming you require a Debian distribution package, follow these simple steps for installation.

To get started, open your terminal with:

Ctrl+Alt+T

Then, run the following command:

$sudo apt-get install synfigstudio

If you run into any problems please share them in the comments below.

Alternatively

Download the latest .deb file for your system from Synfig Studio

Go to your directory where it is downloaded. Usually, it would be in the Downloads folder.

cd ~/Downloads

*Install it using gdebi you can also install using dpkg but gdebi is preferred. (eg. for 32 bit package)

sudo dpkg -i synfigstudio_0.64.0-20130509.master.8_i386.deb

or

sudo gdebi synfigstudio_0.64.0-20130509.master.8_i386.deb

That's all you should need.

Related: How To Download Scribus on Ubuntu