Turn-off Spell Check for Other Languages

I'm working in a new book that I created. The text is in English. There are only maybe 0.3% of the words in German. Inspite of this, the spell check tells me that all words in the vicinity of the single German word are wrong, because they aren't German words. I don't want to spell check in ANY other language. I'm somehow not seeing where I can specify which dictionaries to use in this book to spell check. Only HOW to use them (2 options). I see the ability to turn-off the spell check entirely, but that's undesirable. 

I would have expected to be able to control this "feature". I don't want to have to check a bunch of words, because FrameMaker 2019 thinks I'm doing a polygot book.

Does anyone know if this is possible?