n.
Pronunciation: ' r ā -d ē - ə s
Function: noun
Inflected Form: plural ra · dii \ -d ē - ˌ ī \ also ra · di · us · es
Etymology: Latin, ray, radius
Date: circa 1611
1 : a line segment extending from the center of a circle or sphere to the circumference or bounding surface
2 a : the bone on the thumb side of the human forearm also : a corresponding part of vertebrates above fishes b : the third and usually largest vein of an insect's wing
3 a : the length of a radius <a truck with a short turning radius > b : the circular area defined by a stated radius c : a bounded or circumscribed area
4 : a radial part
5 : the distance from a center line or point to an axis of rotation