Roulette (Fr., a little wheel), a game of chance, which from the end of the 18th century till 1838, when it was forbidden by law, was the principal gambling game in Paris. It was the leading game in the German spas till public gambling was abolished in 1873, is still popular in Italy, and is played to some extent in Great Britain and the United States. It is played on a cloth-covered oblong table, in the centre of which is a round cavity having several copper bands around its sides at equal distances from each other. The sides are fixed, but the bottom is movable round an axis in the centre of the cavity, and around its circumference are 38 holes painted black and red alternately, and numbered from 1 to 36, with two zeros marked 0 and 00. These numbers and zeros are painted on the green cloth, and on the margin of the table are the words impair, manque, rouge, pair, passe, and noir. The manager turns the wheel, at the same time throwing into the cavity in an opposite direction to the movement given to the movable bottom an ivory ball, which when the revolution ceases falls into one of the numbered cells.

The player stakes his money upon one or more numbers, and if the ball falls into the corresponding number or zero, he receives for one number his stake and 35 times more, for two numbers 18 times more, for three numbers 12 times more, and so on, the gain being less as the risk is reduced. If the player stakes upon a column, or 12 numbers, and the ball enters a cell corresponding to one of them, he wins three times the amount of his risk. Or he may stake upon an even number (pair), an odd number (impair), from 1 to 18 inclusive (manque), from 19 to 36 inclusive (passe), or upon the colors rouge and noir. If he ventures upon these six chances and the ball falls into either of the zeros, the stakes may be divided between the banker and the player, or may be "put into prison" for another trial to determine to whom they belong. Some tables have but a single zero, and with 37 cells the amount returned to the winners is but 35 to 1, the bank gaining the difference; with two zeros, the advantage of the bank is proportionately greater; and with the divided chances on pair, impair, etc, the steady gain of the bank is almost certain, and is estimated at 4 per cent. on all the money staked.

In American roulette a 28 instead of 36 table is often used, the banker paying the winner but 27 for 1, thus giving a greater percentage against the player.