As far as my limited knowledge of linguistics goes, the technical term is actually "collocations."
To me, any discussion of this topic that doesn't mention collocations signals an amateurish approach.
I also disagree with the premise that "this was not possible before LLM." That's nonsense. Linguists created many dictionaries of collocations for different languages, so that work is precisely what they did!
(Before any LLM zealots attack me, yes, it is now possible to have a more exhaustive list of collocations thanks to LLMs. This doesn't contradict my point.)
Examples of collocation dictionaries:
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AIUI, collocations are just "words that often go together". It doesn't signal any unconventional meaning to the construction, that would make it a proper idiom.