Main Entry: quad·rant

Pronunciation: \ˈkwä-drənt\

Function: noun

Etymology: Middle English, from Latin quadrant-, quadrans fourth part; akin to Latin quattuor four — more at four

Date: 15th century

1 a : an instrument for measuring altitudes consisting commonly of a graduated arc of 90 degrees with an index or vernier and usually having a plumb line or spirit level for fixing the vertical or horizontal direction b : a device or mechanical part shaped like or suggestive of the quadrant of a circle
2 a : an arc of 90 degrees that is one quarter of a circle b : the area bounded by a quadrant and two radii
3 a : any of the four parts into which a plane is divided by rectangular coordinate axes lying in that plane b : any of the four quarters into which something is divided by two real or imaginary lines that intersect each other at right angles

— qua·dran·tal \kwä-ˈdran-t^əl\ adjective

[quadrant illustration]