What is "quintennial"

Usage examples of "quintennial".

Tribe Camp for the quintennial meeting of the chiefs of all or most of the sixty to seventy clans of horse-nomads that had ruled the plains for most of the five or six hundred years since the fabled Mercan civilization had gone down in death and destruction at the hands of some far-distant enemy who must have suffered equal or worse devastation and decimation, since no invading armies had ever followed up the bombs and plagues.