roulette

A game of chance in which a small ball is made to move round rapidly on a circle divided off into numbered (usually red and black) spaces. When the ball stops, it indicates the result of a variety of wagers permitted by the game.

(figurative) An instance of risk-taking, especially when the downside exceeds the upside (contrary to the game of roulette where only the wager is lost).

The locus of a point on a plane curve that rolls without slipping along another fixed plane curve.

A small toothed wheel used by engravers to roll over a plate in order to produce rows of dots.

A similar wheel used to roughen the surface of a plate, as in making alterations in a mezzotint.

Any of the small incisions on a sheet of stamps, used as an alternative to perforations.

A cylindrical curler for the hair.

To separate or decorate by incisions made with a small toothed wheel.