Install libreoffice-voikko by entering the following commands in the terminal:
sudo apt update sudo apt install libreoffice-voikko
Spellchecker, grammar checker and hyphenator for LibreOffice
LibreOffice is a full-featured office productivity suite that provides a near drop-in replacement for Microsoft(R) Office. . This package contains a libreoffice-voikko, a multi language spellchecker, grammar checker and hyphenator extension for LibreOffice. It uses libvoikko for all linguistic operations. . Based on the configuration of libvoikko, spell checking is supported for multiple languages. Other features are currently available only for Finnish. . NOTE: Usually spell-checking, grammar checking and hyphenation should be automatically activated after installing this package. If this is not the case, go to "Writing Aids" settings in LibreOffice and activate Voikko components manually.