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English definition of “radius”

radius

noun [C] uk   /ˈreɪ.di.əs/ (plural radii) us  

radius noun [C] (DISTANCE)

(the length of) a straight line joining the centre of a circle to its edge or the centre of a sphere to its surface: The radius of this wheel is 30 cm. This wheel has a radius of 30 cm. a distance from a central point: The station, shopping centre and school lie within a one-mile radius of the house.

radius noun [C] (BONE)

specialized anatomy the thicker of the two bones in the lower arm
(Definition of radius from the Cambridge Advanced Learners Dictionary & Thesaurus © Cambridge University Press)
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