primacy (n.)

late 14c., primacie, "preeminent position, supremacy, condition of being first in order, power, or importance," from Old French primacie (14c.; Modern French primatie) and directly from Medieval Latin primatia "office of a church primate" (12c.), from Late Latin primas (genitive primatis) "principal, chief, of the first rank," from primus "first" (see prime (adj.)).