First Order

First Order refers to something ranked at the highest or most fundamental level.

In logic and mathematics, first-order logic deals with individuals and their properties, as opposed to higher-order systems that quantify over predicates or sets.

In science, a first-order reaction depends on a single variable; a first-order approximation is the simplest useful estimate.

More generally, first-order concerns are primary or most important: Safety is a first-order priority.

In Star Wars, the First Order is the authoritarian regime that succeeds the Galactic Empire.