quadrature

noun

• 1 Mathematics the process of constructing a square with an area equal to that of a circle, or of another figure bounded by a curve.

• 2 Astronomy the position of the moon or a planet when it is 90° from the sun as viewed from the earth.

• 3 Electronics a phase difference of 90 degrees between two waves of the same frequency, as in the colour difference signals of a television screen.