Same word as in-curvature:

ambit, arc, arch, bend, bight, bow, camber, catenary, chord, circle, circuit, circumference, compass, concavity, contour, crook, curlicue, curvation, curvature, ellipse, festoon, flexure, hairpin, half-moon, helix, horseshoe, hyperbola, incurvation, incurvature