ether (n.) Look up ether at Dictionary.com
late 14c., "upper regions of space," from Old French ether and directly from Latin aether "the upper pure, bright air," from Greek aither "upper air; bright, purer air; the sky," from aithein "to burn, shine," from PIE root *aidh- "to burn" (see edifice).

In ancient cosmology, the element that filled all space beyond the sphere of the moon, constituting the substance of the stars and planets. Conceived of as a purer form of fire or air, or as a fifth element. From 17c.-19c., it was the scientific word for an assumed "frame of reference" for forces in the universe, perhaps without material properties. The concept was shaken by the Michelson-Morley experiment (1887) and discarded after the Theory of Relativity won acceptance, but before it went it gave rise to the colloquial use of ether for "the radio" (1899).

The name also was bestowed c.1730 (Frobenius; in English by 1757) on a volatile chemical compound known since 14c. for its lightness and lack of color (its anesthetic properties weren't fully established until 1842).
ethereal (adj.) Look up ethereal at Dictionary.com
1510s, "of the highest regions of the atmosphere," from ether + -al (1); extended sense of "light, airy" is from 1590s. Meaning "spiritlike, immaterial" is from 1640s. Related: Ethereally.
etheric (adj.) Look up etheric at Dictionary.com
1878, "pertaining to ether," from ether + -ic. Related: Etherical (1650s).
ethernet (n.) Look up ethernet at Dictionary.com
1980, from ether + ending as in Internet, etc.
ethic (n.) Look up ethic at Dictionary.com
late 14c., ethik "study of morals," from Old French etique (13c.), from Late Latin ethica, from Greek ethike philosophia "moral philosophy," fem. of ethikos "ethical," from ethos "moral character," related to ethos "custom" (see ethos). Meaning "a person's moral principles" is attested from 1650s.
ethical (adj.) Look up ethical at Dictionary.com
c.1600, "pertaining to morality," from ethic + -al (1). Related: Ethicality; ethically.
ethics (n.) Look up ethics at Dictionary.com
"the science of morals," c.1600, plural of Middle English ethik "study of morals" (see ethic). The word also traces to Ta Ethika, title of Aristotle's work.
Ethiop Look up Ethiop at Dictionary.com
late 14c., from Latin Æthiops "Ethiopian, negro," from Greek Aithiops, perhaps from aithein "to burn" + ops "face" (compare aithops "fiery-looking," later "sunburned").
Who the Homeric Æthiopians were is a matter of doubt. The poet elsewhere speaks of two divisions of them, one dwelling near the rising, the other near the setting of the sun, both having imbrowned visages from their proximity to that luminary, and both leading a blissful existence, because living amid a flood of light; and, as a natural concomitant of a blissful existence, blameless, and pure, and free from every kind of moral defilement. [Charles Anthon, note to "The First Six Books of Homer's Iliad," 1878]
Ethiopia Look up Ethiopia at Dictionary.com
Latin Aethiopia, from Greek Aithiopia, from Aithiops (see Ethiop). The native name is Abyssinia.
ethnic (adj.) Look up ethnic at Dictionary.com
late 15c. (earlier ethnical, early 15c.) "pagan, heathen," from Late Latin ethnicus, from Greek ethnikos "adopted to the genius or customs of a people, peculiar to a people," from ethnos "band of people living together, nation, people," properly "people of one's own kind," from PIE *swedh-no-, suffixed form of root *s(w)e- (see idiom). Earlier in English as a noun, "a heathen, pagan, one who is not a Christian or Jew" (c.1400).

In Septuagint, Greek ta ethne translates Hebrew goyim, plural of goy "nation," especially of non-Israelites, hence "Gentile nation, foreign nation not worshipping the true God" (see goy), and ethnikos is used as "savoring of the nature of pagans, alien to the worship of the true God," and as a noun "the pagan, the Gentile." The classical sense of "peculiar to a race or nation" in English is attested from 1851, a return to the word's original meaning; that of "different cultural groups" is 1935; and that of "racial, cultural or national minority group" is American English 1945. Ethnic cleansing is attested from 1991.
Although the term 'ethnic cleansing' has come into English usage only recently, its verbal correlates in Czech, French, German, and Polish go back much further. [Jerry Z. Muller, "Us and Them: The Enduring Power of Ethnic Nationalism," Foreign Affairs, March/April 2008]
ethnicity (n.) Look up ethnicity at Dictionary.com
"ethnic character," 1953, from ethnic + -ity. Earlier it meant "paganism" (1772).
ethno- Look up ethno- at Dictionary.com
word-forming element meaning "race, culture," from Greek ethnos "people, nation, class, caste, tribe; a number of people accustomed to live together" (see ethnic). Used to form modern compounds in the social sciences.
ethnocentric (adj.) Look up ethnocentric at Dictionary.com
1900, from ethno- + -centric; a technical term in social sciences until it began to be more widely used in the second half of the 20th century. Related: Ethnocentricity; ethnocentrism.
ethnography (n.) Look up ethnography at Dictionary.com
1834, perhaps from German Ethnographie; see ethno- + -graphy "the study of." Related: Ethnographer; ethnographic.
ethnology (n.) Look up ethnology at Dictionary.com
1842, from ethno- + -logy. Related: Ethnologist.
ethology (n.) Look up ethology at Dictionary.com
late 17c., "mimicry," from Latin ethologia, from Greek ethologia, from ethos "character" (see ethos). As a branch of zoology, from 1897.
ethos (n.) Look up ethos at Dictionary.com
revived by Palgrave in 1851 from Greek ethos "moral character, nature, disposition, habit, custom," from suffixed form of PIE root *s(w)e- (see idiom). An important concept in Aristotle (as in "Rhetoric" II xii-xiv).
ethyl (n.) Look up ethyl at Dictionary.com
1838, from German ethyl (Liebig, 1834), from ether + -yl. Ethyl alcohol, under other names, was widely used in medicine by 13c.
ethylene (n.) Look up ethylene at Dictionary.com
1852, from ethyl + -ene, probably suggested by methylene.
etic (adj.) Look up etic at Dictionary.com
1954, coined by U.S. linguist K.L. Pike (1912-2000) from ending of phonetic.
etiolate (v.) Look up etiolate at Dictionary.com
of plants, "grown in darkness," 1791, from French étiolé, past participle of étioler "to blanch" (17c.), perhaps literally "to become like straw," from Norman dialect étule "a stalk," Old French esteule "straw, field of stubble," from Latin stipula "straw" (see stipule). Related: Etiolated.
etiology (n.) Look up etiology at Dictionary.com
"science of causes or causation," 1550s, from Late Latin aetiologia, from Greek aitiologia "statement of cause," from aitia "cause" + -logia "a speaking" (see -logy). Related: Etiologic; etiological.
etiquette (n.) Look up etiquette at Dictionary.com
1750, from French étiquette "prescribed behavior," from Old French estiquette "label, ticket" (see ticket).

The sense development in French perhaps is from small cards written or printed with instructions for how to behave properly at court (compare Italian etichetta, Spanish etiqueta), and/or from behavior instructions written on a soldier's billet for lodgings (the main sense of the Old French word).
Etna Look up Etna at Dictionary.com
volcano in Sicily, from Latin Aetna, from an indigenous Sicilian language, *aith-na "the fiery one," from PIE *ai-dh-, from root *ai- "to burn" (see edifice).
Eton Look up Eton at Dictionary.com
collar (1887), jacket (1881, formerly worn by the younger boys there), etc., from Eton College, public school for boys on the Thames opposite Windsor, founded by Henry VI. The place name is Old English ea "river" (see ea) + tun "farm, settlement."
Etruscan (n.) Look up Etruscan at Dictionary.com
1706, from Latin Etruscus "an Etruscan," from Etruria, ancient name of Tuscany, of uncertain origin, but containing an element that might mean "water" (see Basque) and which could be a reference to the rivers in the region.
Etta Look up Etta at Dictionary.com
fem. proper name, originally a shortening of Henrietta.
ettin (n.) Look up ettin at Dictionary.com
an old word for "a giant," extinct since 16c., from Old English eoten "giant, monster," from Proto-Germanic *itunoz "giant" (cognates: Old Norse iotunn, Danish jætte).
etude (n.) Look up etude at Dictionary.com
1837, from French étude, literally "study," from Old French estudie (12c.), from Latin studium (see study (n.)). Popularized in English by the etudes of Chopin (1810-1849).
etui (n.) Look up etui at Dictionary.com
1610s, from French étui, Old French estui (12c.) "case, box, container," back-formation from estuier "put in put aside, spare; to keep, shut up, imprison," of uncertain origin.
etymological (adj.) Look up etymological at Dictionary.com
1590s; see etymology + -ical. Related: Etymologically.
etymologicon (n.) Look up etymologicon at Dictionary.com
"a work in which etymologies are traced," 1640s, from Latin etymologicon, from Greek etymologikon, neuter of etymologikos (see etymology).
etymologist (n.) Look up etymologist at Dictionary.com
1630s; see etymology + -ist. Also etymologer (1640s).
etymologize (v.) Look up etymologize at Dictionary.com
1530s; see etymology + -ize. Related: Etymologized; etymologizing.
etymology (n.) Look up etymology at Dictionary.com
late 14c., ethimolegia "facts of the origin and development of a word," from Old French et(h)imologie (14c., Modern French étymologie), from Latin etymologia, from Greek etymologia, properly "study of the true sense (of a word)," from etymon "true sense" (neuter of etymos "true, real, actual," related to eteos "true") + -logia "study of, a speaking of" (see -logy). Latinized by Cicero as veriloquium.

In classical times, of meanings; later, of histories. Classical etymologists, Christian and pagan, based their explanations on allegory and guesswork, lacking historical records as well as the scientific method to analyze them, and the discipline fell into disrepute that lasted a millennium. Flaubert ["Dictionary of Received Ideas"] perhaps had them in mind when he wrote that the general view was that etymology was "the easiest thing in the world with the help of Latin and a little ingenuity." As a modern branch of linguistic science, from 1640s. Related: Etymological; etymologically.
etymon (n.) Look up etymon at Dictionary.com
"primitive word," 1570s, from Greek etymon, neuter of etymos "true, real, actual," related to eteos "true," which is perhaps cognate with Sanskrit satyah, Gothic sunjis, Old English soð "true."
eu- Look up eu- at Dictionary.com
word-forming element in modern use meaning "good, well," from comb. form of Greek eus "good," eu "well" (adv.), also "luckily, happily," from PIE *(e)su- "good" (cognates: Sanskrit su- "good," Avestan hu- "good").
eubacteria (n.) Look up eubacteria at Dictionary.com
coined in German 1930; see eu- + bacteria.
eucalyptus (n.) Look up eucalyptus at Dictionary.com
1809, from Modern Latin, coined 1788 by French botanist Charles Louis L'héritier de Brutelle (1746-1800) from Greek eu "well" (see eu-) + kalyptos "covered" (see Calypso); so called for the covering on the bud.
Eucharist (n.) Look up Eucharist at Dictionary.com
"sacrament of the Lord's Supper, the Communion," mid-14c., from Old French eucariste, from Late Latin eucharistia, from Greek eukharistia "thanksgiving, gratitude," later "the Lord's Supper," from eukharistos "grateful," from eu "well" (see eu-) + stem of kharizesthai "show favor," from kharis "favor, grace," from PIE root *gher- (5) "to like, want" (see hortatory). Eukharisteo is the usual verb for "to thank, to be thankful" in the Septuagint and New Testament. Related: Eucharistic.
euchre (n.) Look up euchre at Dictionary.com
card game, 1846, American English, of unknown origin.
Euclidean (adj.) Look up Euclidean at Dictionary.com
1650s, "of or pertaining to Euclid," from Greek Eukleides, c.300 B.C.E. geometer of Alexandria. Now often used in contrast to alternative models based on rejection of some of his axioms. His name in Greek means "renowned," from eu "well" (see eu-) + kleos "fame" (see Clio).
eudaemonic (adj.) Look up eudaemonic at Dictionary.com
"producing happiness," 1865, from Greek eudaimonikos "conducive to happiness," from eudaimonia "happiness," from eu (see eu-) + daimon "guardian, genius" (see daimon). Related: Eudaimonia; eudemonia.
Eudora Look up Eudora at Dictionary.com
fem. proper name, from Greek Eudora, literally "generous," fem. of eudoros, from eu "well" (see eu-) + doron "gift" (see date (n.1)).
Eugene Look up Eugene at Dictionary.com
masc. proper name, from French Eugène, from Latin Eugenius, from Greek Eugenios, from eugenes "well-born" (see eugenics).
Eugenia Look up Eugenia at Dictionary.com
fem. proper name, from Latin, from Greek Eugenia, literally "nobility of birth," fem. of Eugenius (see Eugene).
eugenics (n.) Look up eugenics at Dictionary.com
1883, coined (along with adjective eugenic) by English scientist Francis Galton (1822-1911) on analogy of ethics, physics, etc. from Greek eugenes "well-born, of good stock, of noble race," from eu- "good" (see eu-) + genos "birth" (see genus).
The investigation of human eugenics, that is, of the conditions under which men of a high type are produced. [Galton, "Human Faculty," 1883]
euhemerism (n.) Look up euhemerism at Dictionary.com
1846, "the method of regarding myths as glorified accounts of actual events or persons," from Euhemerus of Sicily (4c. B.C.E.), who wrote "Iera Anagraphe," in which he maintained the Greek deities actually were historical mortals. His name is literally "good day," from eu "well" (see eu-) + hemera "day" (see ephemera). Related: Euhemerist; euhemeristic.
eukaryotic (adj.) Look up eukaryotic at Dictionary.com
also eucaryotic, "characterized by well-defined cells (with nuclei and cell walls)," 1957, from French eucaryote (1925), from Greek eu "well" (see eu-) + karyon "nut, kernel" (see karyo-). Related: Eukaryote; eucaryote.
eulogize (v.) Look up eulogize at Dictionary.com
1810, from eulogy + -ize. Related: Eulogized; eulogizing.