Meaning of RADIUS in English
ra ‧ di ‧ us /ˈreɪdiəs/ BrE AmE noun ( plural radii /-diaɪ/) [countable]
[ Date: 1500-1600 ; Language: Latin ; Origin: 'ray, radius' ]
1 . the distance from the centre to the edge of a circle, or a line drawn from the centre to the edge ⇨ diameter
2 . an area that covers a particular distance in all directions from a central point:
The shock of the explosion was felt over a radius of forty miles.
within a 10-mile/200-metre etc radius
There are more than a dozen golf courses within a 15-mile radius of St Andrews.
3 . technical the outer bone of the lower part of your arm
Longman Dictionary of Contemporary English. Longman - Словарь современного английского языка. 2012