- a curve traced by a point on a radius or an extension of the radius of a circle that rolls, without slipping, on a curve, another circle, or a straight line. Equation: x = aθ − b sin θ, y = a − b cos θ.
- rotating on an axis, as a wheel.
- the curve described by a fixed point on the radius or extended radius of a circle as the circle rolls along a straight line
- rotating or capable of rotating about a central axis
- (of a structure or part) resembling or functioning as a pivot or pulley
