Etymology
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radiate (v.)

1610s, "issue or spread in all directions from a point in rays or straight lines," from Latin radiatus, past participle of radiare "to beam, shine, gleam; make beaming," from radius "beam of light; spoke of a wheel" (see radius). Meaning "be radiant, give off rays (of light or heat)" is from 1640s. Related: Radiated; radiates; radiating.

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radiate (adj.)

"having rays, furnished with rays or ray-like parts, shining," 1660s, from Latin radiatus, past participle of radiare "to beam, shine, gleam; make beaming," from radius "beam of light; spoke of a wheel" (see radius).

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radiative (adj.)
"having a tendency to radiate," 1820, from radiate (v.) + -ive. Related: Radiativity.
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radiator (n.)

1832, "any thing which radiates," agent noun in Latin form from radiate (v.). Originally a stove-like apparatus, as a device designed to communicate heat from steam to a room by 1855; the sense of "cooling device in an internal combustion engine" is by 1899.

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irradiate (v.)
c. 1600, "to cast beams of light upon," from Latin irradiatus, past participle of irradiare "shine forth, beam upon, illumine," from assimilated form of in- "into, in" (from PIE root *en "in") + radiare "to shine" (see radiate (v.)). Meaning "expose to radiation other than light" (originally X-rays) is from 1901. Related: Irradiated; irradiating.
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radio- 
word-forming element meaning 1. "ray, ray-like" (see radius); 2. "radial, radially" (see radial (adj.)); 3. "by means of radiant energy" (see radiate (v.)); 4. "radioactive" (see radioactive); 5. "by radio" (see radio (n.)).
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aster (n.)
flower genus, 1706, from Latin aster "star," from Greek aster (from PIE root *ster- (2) "star"); so called for the radiate heads of the flowers. Originally used in English in the Latin sense (c. 1600) but this is obsolete.
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branch (v.)
"send out shoots or new limbs," late 14c., also, of blood vessels, family trees, etc., "to be forked," from branch (n.). Meaning "to spread out from a center, radiate" is from c. 1400. Related: Branched; branching.
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Rig veda 

principal Hindu sacred book, 1776, Reig Beid, from Sanskrit rigveda, from rg- "praise, hymn, spoken stanza," literally "brightness" (from PIE *erkw- "to radiate, beam; praise") + veda "knowledge" (from PIE *weid-o-, from root *weid- "to see"). A thousand hymns, orally transmitted, probably dating from before 1000 B.C.E. Related: Rig-vedic.

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Leo 
zodiac constellation, late Old English, from Latin leo "lion" (see lion). Meaning "person born under the sign of Leo" is from 1894. Leonid "meteor which appears to radiate from Leo" is from 1868; the annual shower peaks Nov. 14 and the stars fall in extreme profusion about every 33 years. The meteors are believed now to be associated with comet Tempel–Tuttle. The dim constellation Leo Minor was introduced 1690 by Hevelius.
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