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.