[ rey-dee-uh s ]
/ ˈreɪ di əs /

noun, plural ra·di·i [rey-dee-ahy] /ˈreɪ diˌaɪ/, ra·di·us·es.

Origin of radius

1590–1600; < Latin: staff, rod, spoke, beam, orig., ray1

Can be confused

circumference diameter radius tangent
Dictionary.com Unabridged Based on the Random House Unabridged Dictionary, © Random House, Inc. 2019

Examples from the Web for radius

British Dictionary definitions for radius


/ (ˈreɪdɪəs) /

noun plural -dii (-dɪˌaɪ) or -diuses

Word Origin for radius

C16: from Latin: rod, ray, spoke
Collins English Dictionary - Complete & Unabridged 2012 Digital Edition © William Collins Sons & Co. Ltd. 1979, 1986 © HarperCollins Publishers 1998, 2000, 2003, 2005, 2006, 2007, 2009, 2012

Medicine definitions for radius


[ rādē-əs ]

n. pl. ra•di•us•es

A line segment that joins the center of a circle with any point on its circumference.
A long, prismatic, slightly curved bone, the shorter and thicker of the two forearm bones, located laterally to the ulna.
The American Heritage® Stedman's Medical Dictionary Copyright © 2002, 2001, 1995 by Houghton Mifflin Company. Published by Houghton Mifflin Company.

Science definitions for radius


[ rādē-əs ]

Plural radii (dē-ī′) radiuses

A line segment that joins the center of a circle or sphere with any point on the circumference of the circle or the surface of the sphere. It is half the length of the diameter.
The shorter and thicker of the two bones of the forearm or the lower portion of the foreleg. See more at skeleton.
The American Heritage® Science Dictionary Copyright © 2011. Published by Houghton Mifflin Harcourt Publishing Company. All rights reserved.