Gist

Etymology

From Anglo-French gist, “it lies” (from Old French gésir, “to lie,” Latin jacēre). It comes from the legal phrase “cest action gist” — “this action lies” — naming the grounds on which a lawsuit rested. From “where the case lies” came “where the essence lies.”

noun · /JIST/
The essential substance or main point of something.
What it names
The take-away core you would keep if you stripped away all detail — the “what it comes down to,” not the decisive point to be argued.
Example
I missed the start of the meeting, so just give me the gist before I say something wrong.
Related idea
The gist is the overall drift; the crux is the single pivotal point on which the matter is decided.