radius
//ˈreɪdiəs//
Noun
radiusSingular
radiiPlural
1
A straight line from the center of a circle or sphere to any point on its circumference or surface.
The radius of this circle is 5 centimeters.
2
The length of such a line; the distance from the center to the edge of a circle or sphere.
The radius of this circle is 5 centimeters.
3
A specified distance from a central point, defining a circular area.
There are several good restaurants within a five-kilometer radius of the hotel.
4
The thicker and shorter of the two bones in the human forearm, on the thumb side.
She fractured her radius when she fell off her bicycle.