iczech software package provides The Czech dictionary for ispell, you can install in your Debian 9 (Stretch) by running the commands given below on the terminal,
$ sudo apt-get update $ sudo apt-get install iczech
iczech is installed in your system.
Make ensure the iczech package were installed using the commands given below,
$ sudo dpkg-query -l | grep iczech *
You will get with iczech package name, version, architecture and description in a table
| Distro | Debian 9 stretch |
| Section | Text Processing |
| Package | iczech |
| Version | 20040229-5.2 |
| Description | The Czech dictionary for ispell |
| Sub Section | Text |