# Online Encyclopedia

# Radius

The word * radius* (Latin for "wheel spoke"; plural

*, pronounced*

**radii***) has several meanings in English:*

**ray**-dee-eye- In classical geometry, a
**radius**of a circle or sphere is any line segment with one endpoint on the circle (i.e., the circular boundary) and the other at the center of the circle. By extension,of a circle or sphere is the length of any such segment.*the*radius

- More generally — in geometry, engineering, graph theory, and many other contexts — the
**radius**of something (e.g. a cylinder, a graph, or a mechanical part) is the distance from its center or axis to its outermost points. See also diameter.

- In anatomy, the
**radius**is one of the two bones of the forearm: see radius (bone).

Last updated: 02-05-2005 11:10:06

Last updated: 03-18-2005 11:16:12