aspell-cy software package provides Welsh dictionary for GNU Aspell, you can install in your Ubuntu 16.10 (Yakkety Yak) by running the commands given below on the terminal,
$ sudo apt-get update $ sudo apt-get install aspell-cy
aspell-cy is installed in your system.
Make ensure the aspell-cy package were installed using the commands given below,
$ sudo dpkg-query -l | grep aspell-cy *
You will get with aspell-cy package name, version, architecture and description in a table
| Distro | Ubuntu 16 10 yakkety yak |
| Section | Text Processing |
| Package | aspell-cy |
| Version | 0.50-3-6 |
| Description | Welsh dictionary for GNU Aspell |
| Sub Section | text |