radius
Definitions
The straight line from the centre of a circle to its edge; its length
半径（圆心到圆周的距离）
A circular area measured from a central point
（从某点算起的）周围范围、半径范围
The shorter, thumb-side bone of the forearm
桡骨（前臂拇指一侧较短的骨头）
Root Breakdown
Root-derivedThe word is the Latin root itself, unchanged. radius meant the spoke of a wheel—the rod from hub to rim. A circle's radius is exactly that: a line from centre to edge. The 'within a 5-mile radius' sense extends it to area, and anatomists named the thumb-side forearm bone radius because it lies along that radial line.
Root radi still carries 9 more wordsUsage Guide
Note the irregular Latin plural: radii ("RAY-dee-eye"), not "radiuses" in technical use. In everyday speech "within a radius of X" describes an area around a point, while in geometry it is a single line/length.
Example Sentences
- 1.
Multiply the radius by two to get the diameter of the circle.
- 2.
There are three good coffee shops within a short radius of the office.
- 3.
She fractured her radius when she fell off her bike.