sweepstakes

a race or other contest for which the prize consists of the stakes contributed by the various competitors.

the prize itself.

a lottery in which winning tickets are selected at random, each winning-ticket number then being matched to one of the horses nominated for or entered in a specific race, and the amounts paid the winners being determined by the finishing order of the horses that run.

lottery ( def 2 ).

any gambling transaction in which each of a number of persons contributes a stake, and the stakes are awarded to one or several winners.

a risky venture that promises large rewards: