From Longman Dictionary of Contemporary Englishrouletterou‧lette /ruːˈlet/ noun [uncountable] 
DGGa game in which a small ball is spun around on a moving wheel, and people try to win money by guessing which hole the ball will fall into
DGGa game in which a small ball is spun around on a moving wheel, and people try to win money by guessing which hole the ball will fall intoExamples from the Corpus
roulette• Half our people starving and the other half standing around a roulette wheel.• Then I sit at a roulette table.• Last week they played a new noise that was obviously the sound of a ball dropping into a roulette wheel.• The effect is rather like the behavior of a roulette ball on a roulette wheel.• Phone calls have become roulette or bingo games.• I hadn't discovered roulette then.• He also spent his evenings at the roulette wheels of Monte Carlo, squandering extravagant sums.• The roulette wheels were sunk in circular pits.Origin roulette (1700-1800) French Old French roele “small wheel”, from Latin rota; → ROTATE 