Noun:

1. a quarter of the circumference of a circle

2. any of the four areas into which a plane is divided by two orthogonal coordinate axes

3. the area enclosed by two perpendicular radii of a circle

4. a measuring instrument for measuring altitude of heavenly bodies

quarter-circlen.[数]四分之一圆周；九十度弧

1. A symbol appears in an upper quadrant of the screen.
   一个符号出现在屏幕上端的四分圆的地方。
2. The line AB lies in the second quadrant.
   线段AB是处在第二象限中。