Why is the ninth month called September?
c.1400, "advancement in rank or position," from Old French promocion "election, promotion" (14c., Modern French promotion) and directly from Latin promotionem (nominative promotio) "a moving forward," noun of action from past participle stem of promovere (see promote). Meaning "advertising, publicity" first recorded 1925.
promotion pro·mo·tion (prə-mō'shən)
The stimulation of the progress or growth of a tumor following initiation by a promoter.