[coordinate systems]
In a rectangular coordinate system, any of the quarters formed by the central intersection of x and y axes that divide a plane into four equal parts.
[Euclidean geometry]
One quarter of a circle measured from the center, having an arc of 90 degrees.
[coordinate systems]
The four divisions of the Cartesian coordinate system, formed by the intersection of the two axes, labeled counterclockwise starting from the upper-right quadrant by the Roman numerals I, II, III, and IV. Because the signs for both coordinates are positive in quadrant I, that is the quadrant used for map grids.
