Mot juste

Etymology

French, "le mot juste," literally "the exact word": mot "word" (from Latin "muttum," a mutter or grunt) plus juste "right, exact" (from Latin "iustus," just). The phrase is bound up with Gustave Flaubert, whose legendary hunt for the perfect word made it a byword for stylistic precision.

noun phrase · /moh ZHOOST/
The single precisely correct word or phrase for a given thought.
What it names
A handle for the writer’s ideal of exactness — reach for it when only one word will do and every near-synonym falls short.
Example
She crossed out "sad," then "forlorn," then "bereft," hunting for the mot juste that would carry the exact weight of the loss.
Related idea
Distinct from a bon mot, which is a witty, quotable remark; the mot juste is about accuracy, not cleverness.