n.  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.  
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.

Noun  1.  curvature  (medicine) a curving or bending; often abnormal; "curvature of the spine" 
2.  curvature  the rate of change (at a point) of the angle between a curve and a tangent to the curve  
3.  curvature  the property possessed by the curving of a line or surface Synonyms: curve 