What does "curvature" mean?

Curvature: (Math.) The amount of degree of bending of a mathematical curve, or the tendency at any point to depart from a tangent drawn to the curve at that point. Aberrancy of curvature (Geom.), the deviation of a curve from a curcular form. -Absolute curvature. See under Absolute. -- Angle of curvature (Geom.), one that expresses the amount of curvature of a curve. -- Chord of curvature. See under Chord. -- Circle of curvature. See Osculating circle of a curve, under Circle. -- Curvature of the spine (Med.), an abnormal curving of the spine, especially in a lateral direction. -- Radius of curvature, the radius of the circle of curvature, or osculatory circle, at any point of a curve.