quadrature

from The American Heritage® Dictionary of the English Language, 5th Edition.

• noun The process of making something square.
• noun Mathematics The process of constructing a square equal in area to a given surface.
• noun Astronomy A configuration in which the position of one celestial body is 90° from another celestial body as measured from a third body, typically Earth.

from The Century Dictionary.

• noun In electricity, phase difference of 90°, or one quarter period.
• noun In geometry, the act of squaring an area; the finding of a square or several squares equal in area to a given surface.
• noun A quadrate; a square space.
• noun The relative position of two planets, or of a planet and the sun, when the difference of their longitudes is 90°.
• noun But when armillæ were employed to observe the moon in other situations … a second inequality was discovered, which was connected, not with the anomalistical, but with the synodical revolution of the moon, disappearing in conjunctions and oppositions, and coming to its greatest amount in quadratures. What was most perplexing about this second inequality was that it did not return in every quadrature, but, though in some it amounted to 2° 39′ , in other quadratures it totally disappeared.
• noun A side of a square.

from the GNU version of the Collaborative International Dictionary of English.

• noun (Math.) The act of squaring; the finding of a square having the same area as some given curvilinear figure; ; 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.
• noun A quadrate; a square.
• noun (Integral Calculus) 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.
• noun (Astron.) 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.
• noun (Astron.) the position of the moon when one half of the disk is illuminated.
• noun (Astron.) a point in an orbit which is at either extremity of the latus rectum drawn through the empty focus of the orbit.

from Wiktionary, Creative Commons Attribution/Share-Alike License.

• noun the process of making something square; squaring
• noun astronomy a situation in which three celestial bodies form a right-angled triangle, the observer being located at the right angle
• noun physics the condition in which the phase angle between two alternating quantities is 90°
• noun art A painting painted on a wooden panel

from WordNet 3.0 Copyright 2006 by Princeton University. All rights reserved.

• noun the construction of a square having the same area as some other figure