aspell-de software package provides German dictionary for aspell, you can install in your Ubuntu 16.04 LTS (Xenial Xerus) by running the commands given below on the terminal,
$ sudo apt-get update $ sudo apt-get install aspell-de
aspell-de is installed in your system.
Make ensure the aspell-de package were installed using the commands given below,
$ sudo dpkg-query -l | grep aspell-de *
You will get with aspell-de package name, version, architecture and description in a table
| Distro | Ubuntu 16 04 lts xenial xerus |
| Section | Text Processing |
| Package | aspell-de |
| Version | 20151222-1 |
| Description | German dictionary for aspell |
| Sub Section | Text |