diameter

名词 diameter:

1. the length of a straight line passing through the center of a circle and connecting two points on the circumference
   同义词：diam
2. 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)

1. The axis of a circle is its diameter.
   圆的轴线是其直径。
2. We must gauge the diameter of wire first.
   我们必须先测量电线的直径。
3. The diameter of the tree-trunk is about 2 meters.
   这树干的直径大约是2米。
4. This lens can magnify 20 diameter.
   这个透镜能放大20倍。

di.am.e.ter

n.（名词）
Abbr. dia.,diam.Mathematics
缩写 dia.,diam.【数学】
A straight line segment passing through the center of a figure, especially of a circle or sphere, and terminating at the periphery.
直径：穿过一图形，特别是圆形或球形的中心到圆周结束的直线段
The length of such a segment.
直径长：这样一段的长度
Thickness or width.
厚度或宽度

来源：
Middle English diametre
中古英语 diametre
from Old French
源自 古法语
from Latin diametrus
源自 拉丁语 diametrus
from Greek diametros
源自 希腊语 diametros
dia- [dia-]
dia- [前缀，表.完全的，有始有终的.]
metron [measure] * see mô- 2
metron [测量] *参见 mô- 2

【引伸】
diam.etral