- radin, paul,
- radio astronomy,
- radio beacon
noun, plural ra·di·i [rey-dee-ahy] /ˈreɪ diˌaɪ/, ra·di·us·es.
Origin of radius
Examples from the Web for radii
These plates strikingly resemble, as already stated, the radii in certain species of Chthamalus.
Yes; and in the same angular relationship to a radii through the center of the head.Warren Commission (3 of 26): Hearings Vol. III (of 15)|The President's Commission on the Assassination of President Kennedy
Shell faintly tinged with purple: radii broad, with their summits not oblique: basis not porose.
The colour is more purple; the summits of the radii perhaps rather less oblique.
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)|Charles Sumner
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).