The suffix -ist adds the sense of person so Deuteronomic text is a text in the tradition and the Deuteronomistic historian is a person writing/editing the text.
I would suggest doing a Logos search on the term "Deuteronomistic" in Heading text. This should give you a half decent start.
Getting a literal definition of Deutronom* is pretty much context based. If someone succeeds in narrowing down the usage ('most scholars'), it lasts only a few paragraphs before fraying at the edges.
Others (hopefully) will point you to the usual discussions. 'Mr. Deuteronomist'. I personally like Kaufman:
https://www.logos.com/product/23076/the-biblical-account-of-the-conquest-of-canaan
The title is apropo, though the discussion hinges on the Deuteronomist. He goes into considerable detail on why he doesn't agree, and therein lies its value. I personally don't agree with him, though I also don't think the deuteronomistic writings favor a deuteronomist (syntax shifts over literary time).
My comments won't satisfy ... again, hopefully others'.
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