A prolate cycloid is a curve traced by a point on a circle that rolls along a straight line, with the circle's center initially above the line. Synonyms for prolate cycloid include a trochoid, trochoidal curve, and roulette. The term trochoid refers to any curve formed by a point on a circle as it rolls along a straight line. The word roulette is used to describe the curve traced by a point on a roulette wheel as it rotates along a straight line. The term trochoidal curve is a generalization of the prolate cycloid that describes any curve formed by a point on a circle as it rolls along a straight line, regardless of the circle's initial position.