**The Collaborative International Dictionary of English v.0.48:**

Curvature \Cur"va*ture\ (k?r"v?-t?r; 135), n. [L. curvatura. See
Curvate.]
1. The act of curving, or the state of being bent or curved;
a curving or bending, normal or abnormal, as of a line or
surface from a rectilinear direction; a bend; a curve.
--Cowper.
[1913 Webster]
The elegant curvature of their fronds. --Darwin.
[1913 Webster]
2. (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.
[1913 Webster]
Aberrancy of curvature (Geom.), the deviation of a curve
from a circular 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.
[1913 Webster]