Quadrature a. : The act of squaring; the finding of a square having the same area as some given curvilinear figure; as, the quadrature of a circle; the operation of finding an expression for the area of a figure bounded wholly or in part by a curved line, as by a curve, two ordinates, and the axis of abscissas.

Quadrature a. : A quadrate; a square.

Quadrature a. : The integral used in obtaining the area bounded by a curve; hence, the definite integral of the product of any function of one variable into the differential of that variable.

Quadrature a. : The position of one heavenly body in respect to another when distant from it 90¡, or a quarter of a circle, as the moon when at an equal distance from the points of conjunction and opposition.

Example:
ASTRONOMY: What does it mean when the moon is a Quadrature?

Taxonomy
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Defination from the web:
Quadrature of the circle (also squaring the circle), in geometry, the problem of constructing a square and circle of equal area, impossible using ... Summing in quadrature means summing the squares of numbers, then taking the square root, as used in error analysis ...