Originally Posted by meme
You can create a dictionary for each book as kiwidude mentioned.
The dictionaries are for the words I want to save.
The ignore list is for words that I do not want to keep, and I do not want to be bothered with a red line, when I'm doing a spell-check of the text.
To be useful as the dictionaries, the menu on spell-check: add to dictionary, should have the option to choose the dictionary.