How to add additional dictionaries to kwrite?

I tried to add dictionaries for non-English languages to kwrite, but I don’t seem to be able to. I suppose I need to install them outside kwrite first. But what package names should I look for? I run Debian and “apt-cache search” doesn’t turn up any obvious candidates. I probably am overlooking something obvious. Can anyone give me a nudge in the right direction please?

The KDE spelling library has aspell and hunspell backends, so you should search for those dictionaries.

Thanks ever so much! aspell was exactly what I was looking for, but couldn’t remember at all.