Paragon
Etymology
Via French from Italian paragone, “touchstone, a testing by comparison,” from paragonare, “to test on a touchstone, compare.” The root idea is comparison against a standard; from “the thing that passes every test” came “a model of perfection.”
noun · /PAIR-uh-gon/
A model of excellence or perfection; the best example of its kind.
What it names
The standard-setting best — not just a good instance but the one held up as the mark others are measured against.
Example
They treated the veteran nurse as a paragon of calm, the person everyone steadied themselves against.
Related idea
An exemplar is simply a typical or representative example; a paragon is specifically the ideal — the best of the best.