sweepstakes (n.)

"prize won in a race or contest," 1773, from Middle English swepestake "one who sweeps or wins all the stakes in a game" (late 14c. as a surname or nickname; late 15c. as the name of one of the King's ships), from swepen "to sweep" (see sweep (v.)) + stake (n.2). Meaning "any race for stakes contributed" is from 1862.