noun, plural ra·di·i [rey-dee-ahy] /ˈreɪ diˌaɪ/, ra·di·us·es.
Origin of radius
Related Words for radiipurview, ambit, span, extension, space, interval, reach, orbit, expanse, limit, extent, compass, boundary, spoke, semidiameter
Examples from the Web for radii
Historical Examples of radii
The edges of the radii are also smooth, as is the edge of the basal cup.
Parietes and basis permeated by pores; radii not permeated by pores.
When the radii are not developed, the sutures are very often obscure.
Not only Massinger, but many of our old writers, use parallels for radii.The Plays of Philip Massinger
In some of the plans the cells are on a circumference, and in some on radii.Charles Sumner; his complete works; Volume 2 (of 20)
noun plural -dii (-dɪˌaɪ) or -diuses
- any radial or radiating part, such as a spoke
- (as modifier)a radius arm
Word Origin for radius
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).