ASL STEM

Definition

The Euclidean plane parametrized by coordinates, so that each point is located based on its position with respect to two perpendicular lines, called coordinate axes. They are two copies of the real line, and the zero point lies at their intersection, called the origin. The coordinate axes are usually called the x-axis and y-axis, depicted above. Point P is associated with the coordinates (x,y) corresponding to its orthogonal projections onto the x-axis and the y-axis respectively.

Source: http://mathworld.wolfram.com/CartesianPlane.html