1. Noun. A quarter of the circumference of a circle.

Exact synonyms: Quarter-circle
Generic synonyms: Line

2. Noun. Any of the four areas into which a plane is divided by two orthogonal coordinate axes.
Generic synonyms: Area, Country

3. Noun. The area enclosed by two perpendicular radii of a circle.
Generic synonyms: Area, Country

4. Noun. A measuring instrument for measuring altitude of heavenly bodies.

1. n. The fourth part; the quarter.

1. Noun. One of the four sections made by dividing an area with two perpendicular lines. ¹

2. Noun. (mathematics) The four regions of the Cartesian plane bounded by the x-axis and y-axis. ¹

3. Noun. (geometry) One fourth of a circle or disc; a sector with an angle of 90°. ¹

4. Noun. (nautical) A measuring device with a graduated arc of 90° used in locating an altitude. ¹

¹ Source: wiktionary.com

1. a quarter section of a circle [n -S]

1. The four parts of your mouth, that is the upper left, the upper right, the lower left, and the lower right. (08 Jan 1998)

Click the following link to bring up a new window with an automated collection of images related to the term: Quadrant Images

Below you will find example usage of this term as found in modern and/or classical literature:

1. A Dictionary of Science, Literature, & Art: Comprising the Definitions and by George William Cox (1867)
"The mural quadrant is of considerable size (six or eight feet radius, ... Ptolemy, in the Almagest, describes a quadrant with which he determined the ..."

2. Plane and Spherical Trigonometry by George Albert Wentworth (1891)
"In the first quadrant, by § 3, the sine increases from 0 to 1, and in the second, decreases from 1 to 0. This is a continually increasing and decreasing ..."

3. The American Journal of the Medical Sciences by Southern Society for Clinical Investigation (U.S.) (1877)
"By paralysis of this muscle and the action of the inferior oblique, the apex of the cornea is turned into the naso-superior quadrant. ..."

4. The English Works of Thomas Hobbes of Malmesbury by Thomas Hobbes (1839)
"strait line AV cut the arch of the quadrant in I PART in. in the same proportion as the point C divides the «—^—^ strait line BV, which is equal to the arch ..."

"45, lateral view of C. quadrant. Fig. 49.—Lateral view of D quadrant in egg of ... D quadrant, a lateral view. Me1 and Me! all dividing bilaterally. Fig. ..."

6. Monthly Notices of the Royal Astronomical Society by Royal Astronomical Society (1866)
"The Astronomer Royal exhibited a quadrant, the work of Abraham Sharp, lately received at the Royal Observatory, Greenwich, and gave the following account of ..."

7. An Universal Etymological English Dictionary ...by Nathan Bailey by Nathan Bailey (1756)
"or or pertaining to Lent. m time» »Г po QUA'DRANT (quadrant, I.. ... Radii perpendicular one to another in the center of a circle, is called a quadrant. ..."

8. The Women's Health and Aging Study: Health and Social Characteristics of ...edited by Jack M. Guralnik, Linda P. Fried, Eleanor M. Simonsick, Judith D. Kasper, Mary E. Lafferty edited by Jack M. Guralnik, Linda P. Fried, Eleanor M. Simonsick, Judith D. Kasper, Mary E. Lafferty (1996)
"The upper quadrant test is negative (no evidence of left or right visual field ... Again look at her eyes and hold your hands in the lower outer quadrant ..."