radius

[rey-dee-uh s]

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


British Dictionary definitions for radiuses

radius

noun plural -dii (-dɪˌaɪ) or -diuses

a straight line joining the centre of a circle or sphere to any point on the circumference or surface
the length of this line, usually denoted by the symbol r
the distance from the centre of a regular polygon to a vertex (long radius) or the perpendicular distance to a side (short radius)
anatomy the outer and slightly shorter of the two bones of the human forearm, extending from the elbow to the wrist
a corresponding bone in other vertebrates
any of the veins of an insect's wing
a group of ray florets, occurring in such plants as the daisy
  1. any radial or radiating part, such as a spoke
  2. (as modifier)a radius arm
the lateral displacement of a cam or eccentric wheel
a circular area of a size indicated by the length of its radiusthe police stopped every lorry within a radius of four miles
the operational limit of a ship, aircraft, etc

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

Word Origin and History for radiuses

radius

n.

1590s, "cross-shaft," from Latin radius "staff, stake, rod; spoke of a wheel; ray of light, beam of light; radius of a circle," of unknown origin. Perhaps related to radix "root," but Tucker suggests connection to Sanskrit vardhate "rises, makes grow," via root *neredh- "rise, out, extend forth;" or else Greek ardis "sharp point."

The geometric sense first recorded 1610s. Plural is radii. Meaning "circular area of defined distance around some place" is attested from 1953. Meaning "shorter bone of the forearm" is from 1610s in English (the Latin word had been used thus by the Romans).

Online Etymology Dictionary, © 2010 Douglas Harper

radiuses in Medicine

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.

radiuses in Science

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.