Abscissa

In mathematics, abscissa (plural abscissae or abscissæ or abscissas) refers to the horizontal coordinate of a point in a two-dimensional rectangular Cartesian coordinate system. The term also refers to the horizontal axis (typically x-axis) of any two-dimensional graph. An ordered pair consists of two terms—the abscissa (horizontal, usually x) and the ordinate (vertical, usually y)—which define the location of a point in two-dimensional rectangular Cartesian coordinate system.

Illustration of a Cartesian coordinate plane. Four points are marked and labeled with their coordinates: (2, 3) in green (quadrant I), (−3, 1) in red (quadrant II), (−1.5, −2.5) in blue (quadrant III), and the origin (0, 0) in purple.

$(\overbrace{x}^\text{abscissa}, \overbrace{y}^\text{ordinate})$

Examples

• For the point (2, 3), 2 is called the abscissa and 3, the ordinate.
• For the point (5, 15), 5 is called the abscissa and 15, the ordinate.