Synaxis of the Archangel Michael and the Other Bodiless Powers

The Synaxis of the Chief of the Heavenly Hosts, Archangel Michael and the Other Heavenly Bodiless Powers: Archangels Gabriel, Raphael, Uriel, Selaphiel, Jehudiel, Barachiel, and Jeremiel was established at the beginning of the fourth century at the Council of Laodicea, which met several years before the First Ecumenical Council. The 35th Canon of the Council of Laodicea condemned and denounced as heretical the worship of angels as gods and rulers of the world, but affirmed their proper veneration.
A Feastday was established in November, the ninth month after March (with which the year began in ancient times) since there are Nine Ranks of Angels. The eighth day of the month was chosen for the Synaxis of all the Bodiless Powers of Heaven since the Day of the Dread Last Judgment is called the Eighth Day by the holy Fathers. After the end of this age (characterized by its seven days of Creation) will come the Eighth Day, and then "the Son of Man shall come in His Glory and all the holy Angels with Him" (Mt. 25:31)

Synaxis: a “gathering together”