before vowels actin-, word-forming element meaning "pertaining to rays," from Latinized form of Greek aktis (genitive aktinos) "ray of light, beam of light; spoke of a wheel;" a word of unknown etymology. It is perhaps cognate with Sanskrit aktuh "light, ray," Gothic uhtwo "dawn, daybreak," Lithuanian anksti "early" [Beekes].
very large ray (also called devilfish), 1760, from Spanish manta "blanket" (which is attested in English from 1748 in this sense, specifically in reference to a type of wrap or cloak worn by Spaniards), from Late Latin mantum "cloak," from Latin mantellum "cloak" (see mantle (n.)). The ray so called "for being broad and long like a quilt" [Jorge Juan and Antonio de Ulloa, "A Voyage to South America"].
sound reproduction system, 1966, named for its inventor, U.S. engineer Ray M. Dolby (b.1933). The surname probably is a variant of Dalby, from the place in Leicestershire.
"negative pole of an electric current," 1834, from Latinized form of Greek kathodos "a going down, a way down," from kata "down" (see cata-) + hodos "a way, path, track, road," a word of uncertain origin (see Exodus). Proposed by the Rev. William Whewell, English polymath, and published by English chemist and physicist Michael Faraday. So called from the path the electric current was supposed to take. Related: Cathodic; cathodal. Cathode ray is attested by 1880, but the phenomenon was known from 1859; cathode ray tube is from 1905.
"emit rays of light," c. 1400, from beam (n.) in the "ray of light" sense. The sense of "shine radiantly" is from 1630s; that of "smile radiantly" is from 1804; that of "to direct radio transmissions" is from 1927. Related: Beamed; beaming.
"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).
1520s, "electric ray" (flat fish that produces an electric charge to stun prey or for defense), from Latin torpedo "electric ray," originally "numbness, sluggishness" (the fish so called from the effect of being jolted by the ray's electric discharges), from torpere "be numb" (from PIE root *ster- (1) "stiff"). The sense of "explosive device used to blow up enemy ships" is first recorded 1776, as a floating mine; the self-propelled version is from c. 1900. Related: Torpedic.
Torpedo. A fish which while alive, if touched even with a long stick, benumbs the hand that so touches it, but when dead is eaten safely. [Johnson]