sweepstakes

from The American Heritage® Dictionary of the English Language, 5th Edition.

• noun plural A lottery in which the participants' contributions form a fund that is awarded as a prize to one or several winners.
• noun plural An event or contest, especially a horserace, the result of which determines the winner of such a lottery.
• noun plural The prize won in such a lottery.

from The Century Dictionary.

• A gaming transaction, in which a number of persons contribute a certain stake, which becomes the property of one or of several of the contributors under certain conditions.
• A prize in a horse-race or other contest, made up of several stakes.
• Same as sweepstake, 1.
• A race for all the stakes contributed, sometimes with money added.

from the GNU version of the Collaborative International Dictionary of English.

• noun A winning of all the stakes or prizes; a sweepstake.
• noun The whole money or other things staked at a horse race, a given sum being put up for each horse, all of which goes to the winner, or is divided among several, as may be previously agreed.
• noun A race for all the sums staked or prizes offered.

from Wiktionary, Creative Commons Attribution/Share-Alike License.

• noun Plural form of sweepstake.

from WordNet 3.0 Copyright 2006 by Princeton University. All rights reserved.

• noun a lottery in which the prize consists of the money paid by the participants