Condiment
Etymology
From Latin "condimentum" (seasoning, spice), from "condire" (to preserve, to pickle, to season). The word gathers under one heading everything that seasons a dish once it is already cooked.
noun · /KON-dih-munt/
A sauce, spread, or seasoning added to finished food by the eater to adjust or heighten its flavor.
What it names
The whole family of after-the-fact flavor tools — ketchup, mustard, hot sauce, chutney — that hand control of the final taste to the diner.
Example
He treats good olive oil as a condiment, drizzling it over the dish right before eating.
Related idea
Distinct from an aromatics base: aromatics are cooked into a dish at the start to build its base, while a condiment is added at the end and can be left off entirely.