Install libgtkspell0 by entering the following commands in the terminal:
sudo apt update sudo apt install libgtkspell0
Description:
spell-checking addon for GTK's TextView widget
GtkSpell provides MSWord/MacOSX-style highlighting of misspelled words in a GtkTextView widget. Right-clicking a misspelled word pops up a menu of suggested replacements.
Version: 2.0.16-1.2
Section: universe/libs