Definition

1. Noun:
   • A measuring instrument for measuring altitude of heavenly bodies: A device, often a quarter of a circle marked with degrees, used in astronomy and navigation to measure angular heights.
   • Any of the four areas into which a plane is divided by two perpendicular coordinate axes: In mathematics, especially in the Cartesian coordinate system, one of the four regions created by the intersection of the x-axis and y-axis.
   • A quarter of the circumference of a circle: An arc equal to 90 degrees, representing one-fourth of a circle's total perimeter.
   • The area enclosed by two perpendicular radii of a circle: A plane figure or sector that is one-fourth of a circular area.

Usage Examples

• As a measuring instrument:
  • The ancient mariner used a quadrant to determine the ship's latitude by measuring the angle of the North Star.
  • The museum displayed a beautifully crafted brass quadrant from the 18th century.
• In mathematics (coordinate geometry):
  • The point (3, 5) lies in the first quadrant of the graph.
  • When plotting the equation, remember that the sine function is positive in the first and second quadrants.
• As a quarter of a circle's circumference or area:
  • The architect designed a garden path in the shape of a quadrant.
  • A quadrant of the circular cake was already eaten.

Advanced Usage

• "First, second, third, fourth quadrant": Standard terms in coordinate geometry to specify the four regions, numbered counterclockwise starting from the upper right.
  • In the second quadrant, x-coordinates are negative and y-coordinates are positive.
• Historical/Scientific Context: Refers to specific historical instruments like the mural quadrant or the Davis quadrant.
  • Tycho Brahe's mural quadrant was a landmark instrument in pre-telescopic astronomy.

Variants and Related Words

• Quadrantal (adj): Pertaining to or shaped like a quadrant.
  • The room had a quadrantal bay window.
• Quadrantid (n): A meteor shower whose radiant appears to lie in the constellation Quadrans Muralis (historically, now part of Boötes).
• Compound Terms:
  • Quadrantanopia (n): A type of visual field loss affecting a quarter of the visual field.
  • Quadrant plate (n): A part in some mechanical devices.

Synonyms

• Quarter: A more general term for one of four equal parts.
• Sector: Specifically refers to a part of a circle enclosed by two radii and an arc, which can be a quadrant if the angle is 90 degrees.

Related Phrases

• "To be in the right quadrant": Often used metaphorically in business or strategy to indicate being in a favorable position, especially when using a 2x2 matrix analysis.
  • Our product is in the high-growth, high-market-share quadrant of the portfolio matrix.

Noun

1. a measuring instrument for measuring altitude of heavenly bodies
2. the area enclosed by two perpendicular radii of a circle
3. any of the four areas into which a plane is divided by two orthogonal coordinate axes
4. a quarter of the circumference of a circle