[quad.rant] n [ME, fr. L quadrant-, quadrans fourth part; akin to L quattuor four--more at four] (15c) 1 a: an instrument for measuring altitudes consisting commonly of a graduated arc of 90 degrees with an index or vernier and usu. 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 adj