promo (n.)

c. 1400, promocioun, "advancement in rank, honor, or position," from Old French promocion "election, promotion" (14c., Modern French promotion) and directly from Latin promotionem (nominative promotio) "advancement, a moving forward," noun of action from past-participle stem of promovere "move forward, advance" (see promote).

From early 15c. as "advancement of a cause; assistance, help, support, encouragement." The meaning "advertising, publicity" first recorded 1925.