The term 'curve shape' can refer to three different shapes: ESS (3 letters), ARC (3 letters), and CATENARY (8 letters). ESS stands for Ellipse, which is a closed curve in a plane surrounding two focal points such that the sum of the distances to the two focal points is constant for every point on the curve. ARC stands for ARC, which is a portion of a curved line that is part of a circle or other curved shape. Finally, CATENARY stands for Catenary, which is the curve formed by a hanging chain or cable supported only at its ends.