Meaning of “radius” - Learner’s Dictionary

radius

noun [ C ] uk us /ˈreɪdiəs/ (plural radii)
POINT

a certain distance from a particular point in any direction:

Most facilities lie within a two-mile radius of the house.
CIRCLE

the distance from the centre of a circle to its edge

(Definition of “radius” from the Cambridge Learner’s Dictionary © Cambridge University Press)