Online Etymology Dictionary

etui (n.): 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.): 1590s; see etymology + -ical. Related: Etymologically.
etymologicon (n.): "a work in which etymologies are traced," 1640s, from Latin etymologicon, from Greek etymologikon, neuter of etymologikos (see etymology).
etymologist (n.): 1630s; see etymology + -ist. Also etymologer (1640s).
etymologize (v.): 1530s; see etymology + -ize. Related: Etymologized; etymologizing.
etymology (n.): 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).

In classical times, of meanings; later, of histories. Latinized by Cicero as veriloquium. As a branch of linguistic science, from 1640s. Related: Etymological; etymologically.
etymon (n.): "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-: 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" (cf. Sanskrit su- "good," Avestan hu- "good").
eubacteria (n.): coined in German 1930; see eu- + bacteria.
eucalyptus (n.): 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.): "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- "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.): card game, 1846, American English, of unknown origin.
Euclidean (adj.): 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.): "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: fem. proper name, from Greek Eudora, literally "generous," fem. of eudoros, from eu "well" (see eu-) + doron "gift" (see date (n.1)).
Eugene: masc. proper name, from French Eugène, from Latin Eugenius, from Greek Eugenios, from eugenes "well-born" (see eugenics).
Eugenia: fem. proper name, from Latin, from Greek Eugenia, literally "nobility of birth," fem. of Eugenius (see Eugene).
eugenics (n.): 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.): 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.): 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.): 1810, from eulogy + -ize. Related: Eulogized; eulogizing.
eulogy (n.): mid-15c., from Latin eulogium, from Greek eulogia "praise; good or fine language," from eu "well" (see eu-) + -logia "speaking" (see -logy). Eu legein meant "speak well of."
Eumenides: Greek, literally "the well-minded ones," a euphemism of the Erinys.
Eunice: fem. proper name, from Latin, from Greek Eunike, literally "victorious," from eu "well" (see eu-) + nike "victory" (see Nike).
eunuch (n.): late 14c., from Middle French eunuque and directly from Latin eunuchus, from Greek eunoukhos "castrated man," originally "guard of the bedchamber or harem," from euno-, comb. form of eune "bed," of unknown origin, + -okhos, from stem of ekhein "to have, hold" (see scheme (n.)).

The Greek and Latin forms of the word were used to translate Hebrew saris, which sometimes meant merely "palace official," in Septuagint and Vulgate, probably without an intended comment on the qualities of bureaucrats.
Eunuches is he þat is i-gilded, and suche were somtyme i-made wardeynes of ladyes in Egipt. [John of Trevisa, translation of Higdon's Polychronicon, 1387]
euphemism (n.): 1650s, from Greek euphemismos "use of a favorable word in place of an inauspicious one," from euphemizein "speak with fair words, use words of good omen," from eu- "good" (see eu-) + pheme "speaking," from phanai "speak" (see fame (n.)).

In ancient Greece, the superstitious avoidance of words of ill-omen during religious ceremonies, or substitutions such as Eumenides "the Gracious Ones" for the Furies (see also Euxine). In English, a rhetorical term at first; broader sense of "choosing a less distasteful word or phrase than the one meant" is first attested 1793. Related: Euphemistic; euphemistically.
euphony (n.): mid-15c., from Middle French euphonie, from Late Latin euphonia, from Greek euphonia "sweetness of voice," from euphonos "well-sounding," from eu- "good" (see eu-) + phone "sound, voice," related to phanai "speak" (see fame (n.)).

Hence, euphonium (1865), the musical instrument. Related: Euphonic; euphonious.
euphoria (n.): 1727, a physician's term for "condition of feeling healthy and comfortable (especially when sick)," medical Latin, from Greek euphoria "power of enduring easily," from euphoros, literally "bearing well," from eu "well" (see eu-) + pherein "to carry" (see infer). Non-technical use, now the main one, dates to 1882 and is perhaps a reintroduction.
euphoric (adj.): 1888, with reference to hashish, from euphoria + -ic. The noun meaning "a drug which causes euphoria" is from 1934.
Euphrates: Old English Eufrate, from Greek Euphrates, from Old Persian Ufratu, perhaps from Avestan huperethuua "good to cross over," from hu- "good" + peretu- "ford." But Kent says "probably a popular etymologizing in O.P. of a local non-Iranian name" ["Old Persian," p.176]. In Akkadian, purattu.
Euphrosyne: name of one of the three Graces in Greek mythology, from Latin, from Greek Euphrosyne, literally "mirth, merriment," from euphron "cheerful, merry, of a good mind," from eu "well" (see eu-) + phren (genitive phrenos) "mind," of unknown origin.
Eurafrican: coined 1890 by anthropologist D.G. Brinton to designate a "race" of dark-skinned people inhabiting both sides of the Mediterranean; it was used 1920s to describe the "colored" population of South Africa, and 1960s with reference to political situations involving both continents; see Euro- + Africa.
Eurasia (n.): from Euro- + Asia. First record seems to be in H. Reusche's "Handbuch der Geographie" (1858), but cf. Eurasian.
Eurasian (n.): 1844, from Euro- + Asian. Originally of children of British-East Indian marriages; sense of "of Europe and Asia considered as one continent" is from 1868.
eureka: c.1600, from Greek heureka "I have found (it)," first person singular perfect active indicative of heuriskein "to find" (see heuristic). Supposedly shouted by Archimedes (c.287-212 B.C.E.) when he solved a problem that had been set to him: determining whether goldsmiths had adulterated the metal in the crown of Hiero II, king of Syracuse.
Euro (n.): name for the basic monetary unit of a pan-European currency, from 1996.
Euro-: before vowels Eur-, word forming element meaning "Europe, European," from comb. form of Europe.
Eurocentric (adj.): 1963, from Euro- + -centric.
Europe: from Latin Europa "Europe," from Greek Europe, of uncertain origin; as a geographic name, first the Homeric hymn to Apollo (522 B.C.E. or earlier):
"Telphusa, here I am minded to make a glorious temple, an oracle for men, and hither they will always bring perfect hecatombs, both those who live in rich Peloponnesus and those of Europe and all the wave-washed isles, coming to seek oracles."
Often explained as "broad face," from eurys "wide" (see aneurysm) + ops "face." But also traditionally linked with Europa, Phoenician princess in Greek mythology. Klein (citing Heinrich Lewy) suggests a possible Semitic origin in Akkad. erebu "to go down, set" (in reference to the sun) which would parallel orient. Another suggestion along those lines is Phoenician 'ereb "evening," hence "west."
European: c.1600, from French Européen, from Latin Europaeus, from Greek Europaios "European," from Europe (see Europe).
europium (n.): rare earth element, 1901, named by its discoverer, French chemist Eugène Demarçay (1852-1903) in 1896, from Europe + -ium.
Eurydice: wife of Orpheus in Greek mythology, from Latin, from Greek Eurydike, literally "wide justice," from eurys "wide" (see aneurysm) + dike "right, custom, usage, law; justice" (cognate with Latin dicere "to show, tell;" see diction).
eurypterid (n.): fossil swimming crustacean of the Silurian and Devonian, 1874, from Greek eurys "broad, wide" (see aneurysm) + pteron "feather, wing" (see pterodactyl); so called from their swimming appendages.
eurythmic (adj.): also eurhythmic, "harmonious," 1831, from Greek eurythmia "rhythmical order," from eurythmos "rhythmical," from eu "well" (see eu-) + rhythmos "rhythm" (see rhythm). Related: Eurythmics (1912); eurythmy.
Eustace: masc. proper name, from Old French Eustace (Modern French Eustache), from Latin Eustachius, probably from Greek eustakhos "fruitful," from eu "well" (see eu-) + stakhys "ear (of grain);" see spike (n.1).
Eustachian tube (n.): so called for Italian physician Bartolomeo Eustachio (d.1574), who discovered the passages from the ears to the throat. His name is from Latin Eustachius (see Eustace).
Euterpe: muse of music, from Greek Euterpe, literally "pleasing," from eu "well" (see eu-) + terpein "to delight, please" (see Terpsichore).
euthanasia (n.): c.1600, from Greek euthanasia "an easy or happy death," from eu- "good" (see eu-) + thanatos "death" (see thanatology). Sense of "legally sanctioned mercy killing" is first recorded in English 1869.
euthanise (v.): chiefly British English spelling of euthanize; for suffix, see -ize. Related: Euthanised; euthanising.
euthanize (v.): by 1915, in place of earlier and etymologically correct euthanatize (1873); see euthanasia + -ize. Related: Euthanized; euthanizing.