Online Etymology Dictionary

eisegesis (n.): the reading of one's own ideas into scripture, 1878, from Greek eis "in, into" + ending from exegesis.
Eisenhower: surname, from German Eisenhauer, literally "iron-cutter, iron-hewer," "perhaps based on Fr. Taillefer" [George F. Jones, "German-American Names," 3rd ed., 2006].
Eisteddfod (n.): "annual assembly of Welsh bards," 1822, from Welsh, literally "session," from eistedd "to sit" (from sedd "seat," cognate with Latin sedere; see sedentary) + bod "to be" (cognate with Old English beon; see be).
either (adj.): Old English ægðer, contraction of æghwæðer "each of two, both," from a "always" (see aye (2)) + ge- collective prefix + hwæðer "which of two, whether" (see whether).

Cognate with Dutch ieder, Old High German eogiwedar, German jeder "either, each, every"). Modern sense of "one or the other of two" is late 13c. Use of either-or to suggest an unavoidable choice between alternatives (1931) in some cases reflects Danish enten-eller, title of an 1843 book by Kierkegaard.
ejaculate (v.): 1570s, "emit semen," from Latin eiaculatus, past participle of eiaculari "to throw out, shoot out," from ex- "out" (see ex-) + iaculari "to throw, hurl, cast, dart," from iaculum "javelin, dart," from iacere "to throw" (see jet (v.)). Only other surviving sense is "exclaim suddenly" (1660s). Related: Ejaculated; ejaculating.
ejaculation (n.): c.1600, of fluids; 1620s, of utterances, from French éjaculation, from éjaculer, from Latin ejaculari (see ejaculate).
eject (v.): mid-15c., from Latin eiectus "thrown out," past participle of eicere "throw out," from ex- "out" (see ex-) + -icere, comb. form of iacere "to throw" (see jet (v.)). Related: Ejected; ejecting.
ejection (n.): 1560s, from Middle French ejection and directly from Latin ejectionem, noun of action from past participle stem of ejicere (see eject). The jet pilot's ejection seat (also ejector seat) is from 1945.
eke (v.): c.1200, eken "to increase, lengthen," north England and E. Midlands variant of echen from Old English ecan, eacan, eacian "to increase," probably from eaca "an increase," from Proto-Germanic *aukan (cf. Old Norse auka, Old Frisian aka, Old High German ouhhon, Gothic aukan), from PIE *aug- "to increase" (see augment).

Now mainly in phrase to eke out (1590s). It means "to make something go further or last longer;" you can eke out your income by taking a second job, but you can't eke out your existence. Related: Eked; eking.
eke (adv.): "also" (obsolete), from Old English eac, cognate with Old Saxon, Old Dutch ok, Old Norse and Gothic auk, Old Frisian ak, Old High German ouh, German auch "also;" probably related to eke (v.).
el (n.): American English abbreviation of elevated railroad, first recorded 1906 in O. Henry.
elaborate (adj.): 1590s, "produced by labor," from Latin elaboratus, past participle of elaborare "to exert oneself" (see elaboration). Meaning "very detailed" is from 1620s.
elaborate (v.): c.1600, "to build up from simple elements," from Latin elaboratus, past participle of elaborare (see elaboration). Meaning "to work out in detail" is attested from 1610s. Related: Elaborated; elaborating.
elaborately (adv.): 1630s, see elaborate (adj.) + -ly (2).
elaboration (n.): 1570s, in a physiological sense relating to tissue development, from Late Latin elaborationem (nominative elaboratio), noun of action from past participle stem of elaborare "work out, produce by labor," from ex- "out" (see ex-) + laborare "to labor" (see labor (v.)).
elan (n.): 1877, from French élan (16c.), "spring, bound, impetus," noun derived from élancer "to rush, dart," from Old French elancer, from e- "out" (see ex-) + lancer "to throw," originally "to throw a lance," from Late Latin lanceare, from Latin lancea (see lance (n.)).
eland (n.): "large South African antelope," 1786, from Dutch eland "elk," from a Baltic source akin to Lithuanian elnias "deer," from PIE *el- "red, brown" (see elk), cognate with first element in Greek Elaphebolion, name of the ninth month of the Attic year (corresponding to late March-early April), literally "deer-hunting (month)." Borrowed earlier as ellan (1610s, via French), ellend, from the German form of the word.
elapse (v.): 1640s, from Middle French elapser, from Latin elapsus, past participle of elabi "slip or glide away, escape," from ex- "out, away" (see ex-) + labi "to slip, glide" (see lapse (n.)). The noun now corresponding to elapse is lapse. Related: Elapsed; elapsing.
elasmosaurus (n.): giant sea reptile from the Mezozoic, 1879, from Modern Latin (coined 1868 by E.D. Cope), from Greek elasmos "metal plate" (from elan "to strike;" see elastic) + -saurus.
elastic (adj.): 1650s, coined in French (1650s) as a scientific term to describe gases, from Modern Latin elasticus, from Greek elastos "ductile, flexible," related to elaunein "to strike, beat out," of uncertain origin. Applied to solids from 1670s. Figurative use by 1859. The noun, "cord or string woven with rubber," is 1847, American English.
elasticity (n.): 1660s; see elastic + -ity.
elate (v.): 1570s, literal, "to raise, elevate," probably from Latin elatus "uplifted, exalted," past participle of effere (see elation), or else a back-formation from elation. Figurative use from 1610s. Related: Elated; elating.
elated (adj.): 1610s, past participle adjective from elate.
elation (n.): late 14c., from Old French elacion "elation, conceit, arrogance, vanity," from Latin elationem (nominative elatio), noun of action from elatus "elevated," form used as past participle of efferre, from ex- "out" + latus (see oblate (n.)), past participle of ferre "carry" (see infer). Metaphoric sense of "lifting spirits" was in Latin and has always been the principal meaning in English.
elbow (n.): c.1200, elbowe, from Old English elnboga, from ell "length of the forearm" + boga "bow, arch," from West Germanic *alinobogan, from Proto-Germanic *elino-bugon, literally "bend of the forearm" (cf. Middle Dutch ellenboghe, Dutch elleboog, Old High German elinbogo, German Ellenbogen, Old Norse ölnbogi).

Second element related to Old English bugan "to bend" (see bow (v.)); first element from *alina "arm," from PIE *el- (1) "elbow, forearm" (see ell (n.1)). Phrase elbow grease "hard rubbing" is attested from 1670s, from jocular sense of "the best substance for polishing furniture." Elbow room attested from mid-16c.
elbow (v.): "thrust with the elbow," c.1600, from elbow (n.). Figurative sense is from 1863. Related: Elbowed; elbowing.
eld: poetic or archaic form of old; in some cases from Old English eald.
elder (adj.): "more old," Old English (Mercian) eldra, comparative of eald, ald (see old); only English survival of umlaut in comparison. Superseded by older since 16c. Elder statesman (1921) originally was a translation of Japanese genro (plural).
elder (n.2): type of berry tree, c.1400, from earlier ellen, from Old English ellæn, ellærn "elderberry tree," origin unknown, perhaps related to alder. Common Germanic, cf. Old Saxon elora, Middle Low German elre, Old High German elira, German Eller, Erle. Related: Elderberry.
elder (n.1): "senior citizen," c.1200, from Old English eldra "older person, parent" (used in biblical translation for Greek presbyter); see elder (adj.). The Old English for "grandfather" was ealdfæder.
elderly (adj.): 1610s, from elder + -ly (1). Old English ealdorlic meant "chief, princely, excellent, authentic." Old English also had related eldernliche "of old time," literally "forefatherly."
eldest (adj.): Old English (Mercian) eldrost, superlative of eald, ald "old" (see old). Superseded by oldest since 16c. Cf. elder (adj.).
eldorado (n.): 1590s, from Spanish El Dorado "the golden one," name given 16c. to country or city believed to lie in the heart of the Amazon jungle, from past participle of dorar "to gild," from Latin deaurare.
Eldred: masc. proper name, from Old English Ealdred, literally "great in counsel," from eald "old, great" (see old) + ræd "advice, counsel" (see read).
eldritch (adj.): c.1500, apparently somehow from elf (cf. Scottish variant elphrish), an explanation OED finds "suitable;" Watkins connects its elements with Old English el- "else, otherwise" and rice "realm."
Eleanor: also Elinor, from Provençal Ailenor, a variant of Leonore, introduced in England by Eleanor of Aquitaine (1122-1204), wife of Henry II. The Old French form of the name was Elienor.
elect (v.): early 15c., from Latin electus, past participle of eligere "to pick out, choose" (see election). Related: Elected; electing.
elect (adj.): early 15c., from Latin electus, past participle of eligere (see election).
electable (adj.): 1758; see elect (v.) + -able. Related: Electability.
election (n.): late 13c., from Anglo-French eleccioun, Old French elecion "choice, election, selection" (12c.), from Latin electionem (nominative electio), noun of action from past participle stem of eligere "pick out, select," from ex- "out" (see ex-) + -ligere, comb. form of legere "to choose, read" (see lecture (n.)). Theological sense is from late 14c.
electioneer (v.): 1760 (implied in electioneering), from election, probably on model of auctioneer (see auction), as the verb engineer was not yet in use.
elective (adj.): early 15c., from Late Latin electivus, from electus, past participle of eligere (see election). In reference to school subjects studied at the student's choice, first recorded 1847. As a noun, from 1701.
elector (n.): mid-15c., from Latin elector "chooser, selecter," agent noun from past participle stem of eligere (see election).
electoral (adj.): 1670s, in reference to Germany, from elector + -al (1). In general sense from 1790. Related: Electorally.
electorate (n.): 1670s, in reference to Germany, from elector + -ate (1). Meaning "whole body of voters" is from 1879.
Electra: daughter of Agamemnon and Clytaemnestra, responsible for the murder of her mother, from Greek Elektra, literally "shining, bright," related to elektor "the beaming sun" and perhaps to elektron "amber." Especially in psychological Electra complex (1913) in reference to a daughter who feels attraction toward her father and hostility to her mother.
electric (adj.): 1640s, first used in English by physician Sir Thomas Browne (1605-1682), apparently coined as Modern Latin electricus (literally "resembling amber") by English physicist William Gilbert (1540-1603) in treatise "De Magnete" (1600), from Latin electrum "amber," from Greek elektron "amber" (Homer, Hesiod, Herodotus), also "pale gold" (a compound of 1 part silver to 4 of gold); of unknown origin.

Originally the word described substances which, like amber, attract other substances when rubbed. Meaning "charged with electricity" is from 1670s; the physical force so called because it first was generated by rubbing amber. In many modern instances, the word is short for electrical. Figurative sense is attested by 1793. Electric toothbrush first recorded 1936; electric typewriter 1958.
electrical (adj.): "relating to electricity, run by electricity," 1746, from electric + -al (1). Earlier (1630s) synonymous with electric. Related: Electrically.
electrician (n.): 1751, "scientist concerned with electricity;" 1869 as "technician concerned with electrical systems;" see electric + -ian.
electricity (n.): 1640s (Browne), from electric + -ity. Originally in reference to friction.