n. the length of a straight line passing through the center of a circle and connecting two points on the circumference
n. a straight line connecting the center of a circle with two points on its perimeter (or the center of a sphere with two points on its surface)
n. 直径
[医] 直经, 径
1. The diameter of the circle is five centimeters.
这个圆的直径是五厘米。
2. To find the area of a circle, you need to know its diameter.
要计算一个圆的面积，你需要知道它的直径。
3. The diameter of the tree trunk was measured to be one meter.
树干的直径被测量为一米。