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.
      
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            The elegant curvature of their fronds. --Darwin.
      
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   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.
      
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   {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.
      
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Chord \Chord\ (k[^o]rd), n. [L chorda a gut, a string made of a
   gut, Gr. chordh`. In the sense of a string or small rope, in
   general, it is written cord. See {Cord}.]
   1. The string of a musical instrument. --Milton.
      
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   2. (Mus.) A combination of tones simultaneously performed,
      producing more or less perfect harmony, as, the common
      chord.
      
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   3. (Geom.) A right line uniting the extremities of the arc of
      a circle or curve.
      
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   4. (Anat.) A cord. See {Cord}, n., 4.
      
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   5. (Engin.) The upper or lower part of a truss, usually
      horizontal, resisting compression or tension. --Waddell.
      
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   {Accidental, Common, & Vocal} {chords}. See under
      {Accidental}, {Common}, and {Vocal}.

   {Chord of an arch}. See Illust. of {Arch}.

   {Chord of curvature}, a chord drawn from any point of a
      curve, in the circle of curvature for that point.

   {Scale of chords}. See {Scale}.
      
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