Online Etymology Dictionary

encyclopedic (adj.): 1824, from encyclopedia + -ic.
end (n.): Old English ende "end, conclusion, boundary, district, species, class," from Proto-Germanic *andja (cf. Old Frisian enda, Old Dutch ende, Dutch einde, Old Norse endir "end;" Old High German enti "top, forehead, end," German ende, Gothic andeis "end"), originally "the opposite side," from PIE *antjo "end, boundary," from root *ant- "opposite, in front of, before" (see ante).

Original sense of "outermost part" is obsolete except in phrase ends of the earth. Sense of "destruction, death" was in Old English. Meaning "division or quarter of a town" was in Old English. The end "the last straw, the limit" (in a disparaging sense) is from 1929.

The phrase end run is first attested 1902 in U.S. football; extended to military tactics in World War II; general figurative sense is from 1968. End time in reference to the end of the world is from 1917. To end it all "commit suicide" is attested by 1911. Be-all and end-all is from Shakespeare ("Macbeth" I.vii.5).
Worldly wealth he cared not for, desiring onely to make both ends meet. [Thomas Fuller, "The History of the Worthies of England," 1662]
end (v.): Old English endian, from the source of end (n.). Related: Ended; ending.
endanger (v.): late 15c., from en- (1) "make, put in" + danger. Related: Endangered; endangering. Endangered species first recorded 1964.
endangerment (n.): 1640s, from endanger + -ment.
endear (v.): 1580s, "to enhance the value of," also "win the affection of," from en- (1) "make, put in" + dear (adj.). Meaning "to make dear" is from 1640s. Related: Endeared; endearing.
endearing (adj.): 1660s, present participle adjective from endear. Related: Endearingly.
endearment (n.): "act of endearing," 1610s, from endear + -ment. Meaning "obligation of gratitude" is from 1620s; that of "action expressive of love" is from 1702.
endeavor (n.): early 15c., "pains taken to attain an object," literally "in duty," from phrase put (oneself) in dever "make it one's duty" (a partial translation of Old French mettre en deveir "put in duty"), from Old French dever "duty," from Latin debere "to owe" (see debt). One's endeavors meaning one's "utmost effort" is from late 15c.
endeavor (v.): c.1400; see endeavor (n.). Related: Endeavored; endeavoring.
endeavour: chiefly British English spelling of endeavor (q.v.); for spelling, see -or. Related: Endeavoured; endeavoring; endeavours.
ended (adj.): "finished, completed," 1590s, past participle adjective from end (v.).
endemic (n.): 1660s, from Greek endemos "native, dwelling in (a place), of or belonging to a people" (from en "in;" see en- (2) + demos "people, district;" see demotic) + -ic. From 1759 as an adjective. Endemical is attested from 1650s.
endgame (n.): 1884, from chess, from end + game (n.). There is no formal or exact definition of it in chess, but it begins when most of the pieces have been cleared from the board.
ending (n.): "a coming to an end," Old English endunge, verbal noun from end (v.).
endive (n.): late 14c., from Old French endive, from Medieval Latin endiva or Late Latin intibus, perhaps from Medieval Greek entybon (though OED considers this a borrowing from Latin), which is perhaps of Eastern origin (perhaps from Egyptian tybi "January," which is when the plant grows in Egypt).
endless (adj.): Old English endeleas; see end (n.) + -less. Related: Endlessly. Old English used endeleasnes for "infinity, eternity."
endlong (adv.): Old English andlang "from end to end, lengthwise" (see along) with Middle English substitution of ende (see end (n.)) for first element. Meaning "at full length, horizontally" is from early 15c. In Middle English frequently paired with overthwart and together meaning "lengthwise and crosswise," hence "in all directions." As a preposition c.1200. see along.
endo-: word-forming element meaning "inside, within, internal," comb. form of Greek endon "in, within," literally "in the house of," from en "in" (see en- (2)) + base of domos "house" (see domestic).
endocrine (adj.): "secretly, internally," 1914, from endo- + Latinized form of Greek krinein "to separate, distinguish" (see crisis).
endocrinology (n.): 1919, from endocrine + -ology. Related: Endocrinologist.
endoderm (n.): 1835, from endo- + -derm. Coined by Prussian embryologist Robert Remak (1815-1865).
endogamy (n.): 1865, from endogamous (1865); for which see endo- + gamete.
endogenous (adj.): 1830, from endo- "within" + -genous "producing."
endometrium (n.): 1882, medical Latin, from endo- + Greek metra "uterus," related to meter (see mother (n.1)).
endomorph (n.): 1940 as one of W.H. Sheldon's three types of human bodies, from endo- + Greek morphe "form" (see Morpheus). Related: Endomorphic.
endorphin (n.): 1975, from French endorphine, from endogène "endogenous, growing within" (see endo- + genus) + (mo)rphine.
endorse (v.): late 14c. endosse "alteration," from Old French endosser (12c.), literally "to put on back," from en- "put on" (see en- (1)) + dos "back," from Latin dossum, variant of dorsum.

Sense of "confirm, approve" (by signing on the back) is recorded in English first in 1847. Assimilated 16c. in form to Medieval Latin indorsare. Related: Endorsed; endorsing.
You can endorse, literally, a cheque or other papers, &, metaphorically, a claim or argument, but to talk of endorsing material things other than papers is a solecism. [Fowler]
endorsement (n.): 1540s, from endorse + -ment. Earlier endosement (early 15c.).
endoscopy (n.): 1861, from endo- + -oscopy (see -scope).
endoskeleton (n.): 1838, from endo- + skeleton.
endosperm (n.): 1819, perhaps from German, from endo- + sperm.
endospore (n.): 1859, perhaps from French, from endo- + spore.
endothermic (adj.): 1884, from French endothermique (1879); see endo- + thermal.
endow (v.): late 14c., indowen "provide an income for," from Anglo-French endover, from en- "in" + Old French douer "endow," from Latin dotare "bestow" (see dowry). Related: Endowed; endowing.
endowed (adj.): 1700, past participle adjective from endow.
endowment (n.): mid-15c., "action of endowing," from endow + -ment. Meaning "property with which an institution or person is endowed" is from 1590s; that of "gift, power, advantage" is early 17c.
endpoint (n.): also end-point, 1899, originally in chemistry, from end + point (n.). General use from 1920s.
endue (v.): also indue, c.1400, from Old French enduire "lead, drive, initiate, indoctrinate" (12c.), from Latin inducere "to lead" (see induce). Related: Endued.
endurable (adj.): c.1600, "able to endure," from endure + -able. Meaning "able to be endured" is from c.1800. Related: Endurably.
endurance (n.): late 15c., "continued existence in time;" see endure + -ance. Meaning "ability to endure suffering, etc." is from 1660s.
endure (v.): early 14c., "to undergo or suffer" (especially without breaking); late 14c. "to continue in existence," from Old French endurer (12c.) "make hard, harden; bear, tolerate; keep up, maintain," from Latin indurare "make hard," in Late Latin "harden (the heart) against," from in- (see in- (2)) + durare "to harden," from durus "hard," from PIE *deru- "be firm, solid."

Replaced the important Old English verb dreogan (past tense dreag, past participle drogen), which survives in dialectal dree. Related: Endured; endures.
enduring: late 14c., action of the verb endure; as a present participle adjective meaning "lasting," from 1530s.
Endymion: beautiful youth loved by Moon-goddess Selene, from Greek, perhaps literally "diver, plunger," from endyein "to enter into, sink into, plunge, dive," which was used in reference to the sun or stars setting into the sea. On this theory, he originally was a solar deity, a personification of the setting sun.
enema (n.): early 15c., via Medieval Latin, from Greek enema "injection," from enienai "to send in, inject," from en "in" (see en- (2)) + hienai "send" (cognate of Latin iacere; see jet (v.)).
enemy (n.): early 13c., from Old French enemi (12c.), earlier inimi (9c.) "enemy, adversary, foe, demon, the Devil," from Latin inimicus "hostile, unfriendly; an enemy" (source of Italian nemico, Catalan enamic, Spanish enemigo, Portuguese inimigo), from in- "not" (see in- (1)) + amicus "friend" related to amare "to love" (see Amy).

Most words for "personal enemy" cover also "enemy in war," but certain languages have special terms for the latter, e.g. Greek polemioi (distinct from ekhthroi), Latin hostis, originally "stranger" (distinct from inimicus), Russian neprijatel' (distinct from vrag).

Russian vrag (Old Church Slavonic vragu) is cognate with Lithuanian vargas "misery" (see urge), and probably is related to Proto-Germanic *wargoz, source of Old Norse vargr "outlaw," hence "wolf;" Icelandic vargur "fox," Old English wearg "criminal, felon;" which likely were the inspirations for J.R.R. Tolkien's warg "a kind of large ferocious wolf" in "The Hobbit" (1937) and "Lord of the Rings." Related: Enemies.
energetic (adj.): 1650s, "powerful," from Greek energetikos "active," from energein "to work, act upon" (see energy). Of persons, "active," in English from 1796 (energetical is from c.1600).
energize (v.): 1752; see energy + -ize. Related: Energized; energizing.
energizer (n.): 1750, agent noun from energize.
energy (n.): 1590s, "force of expression," from Middle French énergie (16c.), from Late Latin energia, from Greek energeia "activity, operation," from energos "active, working," from en "at" (see en- (2)) + ergon "work, that which is wrought; business; action" (see urge (v.)).

Used by Aristotle with a sense of "force of expression;" broader meaning of "power" is first recorded in English 1660s. Scientific use is from 1807. Energy crisis first attested 1970.