late 14c., "one who promotes" (the interest of someone), "supporter," agent noun from promote, and also from Old French promoteur and directly from Medieval Latin promotor. Specific financial sense of "one who leads in forming a company" is from 1876; sense of "one who organizes sporting or entertainment events" is attested from 1936.
promissory
promnesia
promo
promontory
promote
promoter
promotion
promotional
prompt
prompter
promptness