Abscissa

In mathematics, abscissa or abscissae refers to the first element of an ordered pair.

It is the first of the two terms by which a point is referred to, in a system of fixed rectilinear coordinate (Cartesian coordinate) axes. The abscissa is also known as the "x" coordinate of a point.

Examples

 * The point (12, -18) has an abscissa of 12.
 * The point (-7, 3) has an abscissa of -7.