Quiz: Remember the definition of mal de mer?
(After Renee Descartes, French philosopher and mathematician) A pair of numbers, (x, y), defining the position of a point in a two-dimensional space by its perpendicular projection onto two axes which are at right angles to each other. x and y are also known as the abscissa and ordinate.
The idea can be generalised to any number of independent axes.
Compare polar coordinates.