arc

An arc is a simple curve which does not change its direction and does not form a closed loop. It may appear like a C or a U, like a crescent moon, or a similar shape. The ends may be squared, rounded, pointed, or virtually any other shape, as long as the predominant shape resembles an arc in its simplified form.

The main curve can resemble a crescent, C, or U. The shape of its ends can vary while the overall plan follows the same unclosed curve.

A wave reverses its direction of curvature at successive bends. A circle forms a closed rounded outline, so its perimeter has a different overall arrangement from an open arc.