install additional language Spell-checks on Debian
Some applications on Debian got spell-checking built in. eg. LibreOffice, vim, etc. There are a couple of libraries for spell-checking packaged for Debian. Sofar I'm aware of three. So this is what I install to make sure I've got German spell-checking available in most applications:
# install de dictionaries for most apps:
sudo apt install aspell-de myspell-de-de hunspell-de-de
# libre office needs some extra love thou:
sudo apt install --install-suggests libreoffice-l10n-de