The Italian monolingual dictionary
was good.
It seems that after firmware 3.17.3 it has been replaced with a concise version.

The original dicthtml-it.zip was about 12 mb.
The new one is about 2.6mb.
In Kobo Aura H2O anyway you can replace the new one with the old one that you can find here
https://www.mobileread.com/forums/sho...d.php?t=196931
I don't know if you can do the same with the new Kobo devices.