aspell-it software package provides Italian dictionary for GNU 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-it
aspell-it is installed in your system.
Make ensure the aspell-it package were installed using the commands given below,
$ sudo dpkg-query -l | grep aspell-it *
You will get with aspell-it package name, version, architecture and description in a table
| Distro | Ubuntu 16 04 lts xenial xerus |
| Section | Text Processing |
| Package | aspell-it |
| Version | 2.4-20070901-0-2.1 |
| Description | Italian dictionary for GNU Aspell |
| Sub Section | Text |