Source : Webster's Revised Unabridged Dictionary (1913)

Cartesian \Car*te"sian\, a. [From Renatus Cartesius, Latinized
   from of Ren['e] Descartes: cf. F. cart['e]sien.]
   Of or pertaining to the French philosopher Ren['e] Descartes,
   or his philosophy.

         The Cartesion argument for reality of matter. --Sir W.
                                                  Hamilton.

   {Cartesian co["o]rdinates} (Geom), distance of a point from
      lines or planes; -- used in a system of representing
      geometric quantities, invented by Descartes.

   {Cartesian devil}, a small hollow glass figure, used in
      connection with a jar of water having an elastic top, to
      illustrate the effect of the compression or expansion of
      air in changing the specific gravity of bodies.

   {Cartesion oval} (Geom.), a curve such that, for any point of
      the curve mr + m'r' = c, where r and r' are the distances
      of the point from the two foci and m, m' and c are
      constant; -- used by Descartes.



   Note: Co["o]rdinates are of several kinds, consisting in some
         of the different cases, of the following elements,
         namely:
      (a) (Geom. of Two Dimensions) The abscissa and ordinate of
          any point, taken together; as the abscissa PY and
          ordinate PX of the point P (Fig. 2, referred to the
          co["o]rdinate axes AY and AX.
      (b) Any radius vector PA (Fig. 1), together with its angle
          of inclination to a fixed line, APX, by which any
          point A in the same plane is referred to that fixed
          line, and a fixed point in it, called the pole, P.
      (c) (Geom. of Three Dimensions) Any three lines, or
          distances, PB, PC, PD (Fig. 3), taken parallel to
          three co["o]rdinate axes, AX, AY, AZ, and measured
          from the corresponding co["o]rdinate fixed planes,
          YAZ, XAZ, XAY, to any point in space, P, whose
          position is thereby determined with respect to these
          planes and axes.
      (d) A radius vector, the angle which it makes with a fixed
          plane, and the angle which its projection on the plane
          makes with a fixed line line in the plane, by which
          means any point in space at the free extremity of the
          radius vector is referred to that fixed plane and
          fixed line, and a fixed point in that line, the pole
          of the radius vector.

   {Cartesian co["o]rdinates}. See under {Cartesian}.

   {Geographical co["o]rdinates}, the latitude and longitude of
      a place, by which its relative situation on the globe is
      known. The height of the above the sea level constitutes a
      third co["o]rdinate.

   {Polar co["o]rdinates}, co["o]rdinates made up of a radius
      vector and its angle of inclination to another line, or a
      line and plane; as those defined in
      (b) and
      (d) above.

   {Rectangular co["o]rdinates}, co["o]rdinates the axes of
      which intersect at right angles.

   {Rectilinear co["o]rdinates}, co["o]rdinates made up of right
      lines. Those defined in
      (a) and
      (c) above are called also {Cartesian co["o]rdinates}.

   {Trigonometrical} or {Spherical co["o]rdinates}, elements of
      reference, by means of which the position of a point on
      the surface of a sphere may be determined with respect to
      two great circles of the sphere.

   {Trilinear co["o]rdinates}, co["o]rdinates of a point in a
      plane, consisting of the three ratios which the three
      distances of the point from three fixed lines have one to
      another.



   Note: Co["o]rdinates are of several kinds, consisting in some
         of the different cases, of the following elements,
         namely:
      (a) (Geom. of Two Dimensions) The abscissa and ordinate of
          any point, taken together; as the abscissa PY and
          ordinate PX of the point P (Fig. 2, referred to the
          co["o]rdinate axes AY and AX.
      (b) Any radius vector PA (Fig. 1), together with its angle
          of inclination to a fixed line, APX, by which any
          point A in the same plane is referred to that fixed
          line, and a fixed point in it, called the pole, P.
      (c) (Geom. of Three Dimensions) Any three lines, or
          distances, PB, PC, PD (Fig. 3), taken parallel to
          three co["o]rdinate axes, AX, AY, AZ, and measured
          from the corresponding co["o]rdinate fixed planes,
          YAZ, XAZ, XAY, to any point in space, P, whose
          position is thereby determined with respect to these
          planes and axes.
      (d) A radius vector, the angle which it makes with a fixed
          plane, and the angle which its projection on the plane
          makes with a fixed line line in the plane, by which
          means any point in space at the free extremity of the
          radius vector is referred to that fixed plane and
          fixed line, and a fixed point in that line, the pole
          of the radius vector.

   {Cartesian co["o]rdinates}. See under {Cartesian}.

   {Geographical co["o]rdinates}, the latitude and longitude of
      a place, by which its relative situation on the globe is
      known. The height of the above the sea level constitutes a
      third co["o]rdinate.

   {Polar co["o]rdinates}, co["o]rdinates made up of a radius
      vector and its angle of inclination to another line, or a
      line and plane; as those defined in
      (b) and
      (d) above.

   {Rectangular co["o]rdinates}, co["o]rdinates the axes of
      which intersect at right angles.

   {Rectilinear co["o]rdinates}, co["o]rdinates made up of right
      lines. Those defined in
      (a) and
      (c) above are called also {Cartesian co["o]rdinates}.

   {Trigonometrical} or {Spherical co["o]rdinates}, elements of
      reference, by means of which the position of a point on
      the surface of a sphere may be determined with respect to
      two great circles of the sphere.

   {Trilinear co["o]rdinates}, co["o]rdinates of a point in a
      plane, consisting of the three ratios which the three
      distances of the point from three fixed lines have one to
      another.

Source : Free On-Line Dictionary of Computing

Cartesian coordinates
     
         (After Renee Descartes, French
        philosopher and mathematician) A pair of numbers, (x, y),
        defining the position of a point in a two-dimensional space by
        its perpendicular projection onto two axes which are at right
        angles to each other.  x and y are also known as the
        {abscissa} and {ordinate}.
     
        The idea can be generalised to any number of independent axes.
     
        Compare {polar coordinates}.
     
        (1997-07-08)