# quadrant

[kwod-ruh nt]

- a quarter of a circle; an arc of 90°.
- the area included between such an arc and two radii drawn one to each extremity.
- something shaped like a quarter of a circle, as a part of a machine.
- Geometry, Astronomy. one of the four parts into which a plane, as the face of a heavenly body, is divided by two perpendicular lines, numbered counterclockwise from upper right: the first quadrant of the moon.
- an instrument, usually containing a graduated arc of 90°, used in astronomy, navigation, etc., for measuring altitudes.
- Astrology. one of the four quarters of the horoscope: determined by the ascendant, nadir, descendant, and midheaven and numbered counterclockwise from the ascendant.
- Furniture. one of two metal sliding pieces, of quadrant form, used to support the fall front of a desk from above.

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## Origin of quadrant^{}

1350–1400; Middle English < Latin quadrant- (stem of quadrāns) fourth part

Dictionary.com Unabridged
Based on the Random House Unabridged Dictionary, © Random House, Inc. 2018

## Examples from the Web for quadrantal

### Historical Examples

#### The errors of the compass in an iron ship are mainly the semicircular error and the quadrantal error.

Lord KelvinAndrew Gray

## quadrant

- geometry
- a quarter of the circumference of a circle
- the area enclosed by two perpendicular radii of a circle and its circumference
- any of the four sections into which a plane is divided by two coordinate axes

- a piece of a mechanism in the form of a quarter circle, esp one used as a cam or a gear sector
- an instrument formerly used in astronomy and navigation for measuring the altitudes of stars, consisting of a graduated arc of 90° and a sighting mechanism attached to a movable arm

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## Word Origin

C14: from Latin quadrāns a quarter

Collins English Dictionary - Complete & Unabridged 2012 Digital Edition
© William Collins Sons & Co. Ltd. 1979, 1986 © HarperCollins
Publishers 1998, 2000, 2003, 2005, 2006, 2007, 2009, 2012

## Word Origin and History for quadrantal

## quadrant

### n.

late 14c., "a quarter of a day, six hours," from Middle French quadrant, from Latin quadrantem (nominative quadrans) "fourth part," also the name of a coin worth a quarter of an as, noun use of present participle of quadrare "to make square; put in order, arrange, complete; run parallel, be exact," figuratively "to fit, suit, be proper," related to quadrus "a square," quattuor "four" (see four). The surveying instrument is first so called c.1400, because it forms a quarter circle. Related: Quadrantal.

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Online Etymology Dictionary, © 2010 Douglas Harper

## quadrant

(kwŏd′rənt)- A circular arc of 90 degrees; one fourth of the circumference of a circle.
- A quarter portion of any roughly circular anatomical area such as the abdomen, measuring along imaginary axes at right angles to each other.

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The American Heritage® Stedman's Medical Dictionary
Copyright © 2002, 2001, 1995 by Houghton Mifflin Company. Published by Houghton Mifflin Company.

## quadrant

[kwŏd′rənt]

- An arc equal to one quarter of the circumference of a circle; an arc of 90°.
- Any of the four regions into which a plane is divided by the axes of a Cartesian coordinate system. The quadrants are numbered counterclockwise one through four, beginning with the quadrant in which both the x- and y-coordinates are positive (usually the upper right quadrant).
- A navigational instrument similar to a sextant but with an arc of 90° rather than 60°. See more at sextant.

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The American Heritage® Science Dictionary
Copyright © 2011. Published by Houghton Mifflin Harcourt Publishing Company. All rights reserved.