Oh, such a brilliant idea!
I had not even thought to add it to the dictionary in some places.
In Gmail, it was an easy right-click on the word, then
Add to dictionary, and no more red squiggly line. Sweet!
In MS Word, it recognized permaculture was spelled correctly - no squiggles.
In Google (Drive) Doc, it also recognized permaculture was spelled correctly - no squiggles.
Where else might the dictionary update make a difference?