In common usage, the abscissa refers to the (x) coordinate and the ordinate refers to the (y) coordinate of a standard two-dimensional graph.

The distance of a point from the y-axis, scaled with the x-axis, is called the abscissa or x coordinate of the point. The distance of a point from the x-axis scaled with the y-axis is called the ordinate or y coordinate of the point.

For example, if (x, y) is an ordered pair in the Cartesian plane, then the first coordinate in the plane (x) is called the abscissa and the second coordinate (y) is the ordinate.

In mathematics, the abscissa (; plural abscissae or abscissas) and the ordinate are respectively the first and second coordinate of a point in a Cartesian coordinate system:

abscissa ${\displaystyle \equiv x}$-axis (horizontal) coordinate

ordinate ${\displaystyle \equiv y}$-axis (vertical) coordinate

Usually these are the horizontal and vertical coordinates of a point in plane, the rectangular coordinate system. 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 space:

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

The abscissa of a point is the signed measure of its projection on the primary axis, whose absolute value is the distance between the projection and the origin of the axis, and whose sign is given by the location on the projection relative to the origin (before: negative; after: positive).

The ordinate of a point is the signed measure of its projection on the secondary axis, whose absolute value is the distance between the projection and the origin of the axis, and whose sign is given by the location on the projection relative to the origin (before: negative; after: positive).