The x-axis is the horizontal axis of a two-dimensional plot in Cartesian coordinates that is conventionally oriented to point to the right. In three dimensions, the x-, y-, and z - are usually arranged so as to form a right-handed coordinate system. Physicists and astronomers sometimes call this axis the abscissa, although that term is more commonly used to refer to coordinates along the x-axis.

abscissa | ordinate | origin | right-handed coordinate system | y-axis | z-axis