Entry 2 senses · 2 variants Webster, 1913 fifty-fifty · IPA adj. n. 01 adj. equally large; -- of probabilities. 1. equally large; -- of probabilities. Syn. even. 02 n. a lottery in which the organizers retain fifty percent of the money wagered, and distribute fifty percent of the wagered money to the winner. 1. a lottery in which the organizers retain fifty percent of the money wagered, and distribute fifty percent of the wagered money to the winner.