Online Etymology Dictionary

extermination (n.): mid-15c., "repulsion;" 1540s, "utter destruction," from Middle French extermination and directly from Latin exterminationem (nominative exterminatio), noun of action from past participle stem of exterminare (see exterminate).
exterminator (n.): c.1400, "an angel who expells (people from a country)," from Late Latin exterminator, from Latin exterminatus, past participle stem of exterminare (see exterminate). As a substance for ridding a place of rats, etc., by 1848. As a person whose job it is to do this, by 1938.
extern (n.): "outsider," c.1600, from French externe, from Latin externus (see external).
external (adj.): early 15c. (implied in externalle), from Middle French externe or directly from Latin externus "outside, outward" (from exterus; see exterior) + -al (1). This version won out over exterial. Related: Externally.
externality (n.): 1713, from external + -ity.
externalize (v.): 1852, from external + -ize. Related: Externalized; externalizing.
extinct (adj.): early 15c., from Latin extinctus/exstinctus, past participle of extinguere/exstinguere (see extinguish). Originally of fires; the sense of the condition of "dying out" of a family or a hereditary title, 1580s; of species by 1768. Cf. extinction.
extinction (n.): early 15c., from Latin extinctionem/exstinctionem (nominative extinctio/exstinctio), noun of action from past participle stem of extinguere/exstinguere (see extinguish). Originally of fires, lights; figurative use, of wiping out a material thing (a debt, a person, a family, etc.) from early 17c.; of species by 1784.
extinguish (v.): c.1500 (implied in extinguishable), from Latin extinguere/exstinguere "quench, wipe out, obliterate," from ex- "out" (see ex-) + stinguere "quench," from PIE *steig- "to prick, stick, pierce." Related: Extinguished; extinguishing.
extinguisher (n.): 1550s, agent noun from extinguish. As a mechanical device for putting out fires, from 1887.
extirpate (v.): 1530s, usually figurative, from Latin extirpatus/exstirpatus, past participle of extirpare/exstirpare (see extirpation). Related: Extirpated; extirpating.
extirpation (n.): early 15c., "removal;" 1520s, "rooting out, eradication," from Latin extirpationem/exstirpationem (nominative extirpatio/exstirpatio), noun of action from past participle stem of extirpare/exstirpare "root out," from ex- "out" (see ex-) + stirps (genitive stirpis) "a root, stock of a tree."
extol (v.): also extoll, c.1400, "to lift up," from Latin extollere "to place on high, raise, elevate," figuratively "to exalt, praise," from ex- "up" (see ex-) + tollere "to raise," from PIE *tel-, *tol- "to bear, carry" (cf. Greek talantos "bearing, suffering," tolman "to carry, bear," telamon "broad strap for bearing something," Atlas "the 'Bearer' of Heaven;" Lithuanian tiltas "bridge;" Sanskrit tula "balance," tulayati "lifts up, weighs;" Latin tolerare "to bear, support," latus "borne;" Old English þolian "to endure;" Armenian tolum "I allow"). Figurative sense of "praise highly" in English is first attested c.1500. Related: Extolled; extolling.
extoll: variant of extol.
extort (v.): 1520s (as a past participle adj. from early 15c.), from Latin extortus, past participle of extorquere (see extortion). Related: Extorted; extorting.
extortion (n.): c.1300, from Latin extortionem (nominative extortio) "a twisting out, extorting," noun of action from past participle stem of extorquere "wrench out, wrest away, to obtain by force," from ex- "out" (see ex-) + torquere "to twist" (see thwart).
extortionate (adj.): 1789, from extortion + -ate.
extortionist (n.): 1885, from extortion + -ist. Earlier in the same sense were extorter (1590s), extortioner (late 14c.).
extra: 1650s as a stand-alone adjective; also used as an adverb and noun in 17c. (see extra-); modern usages -- including sense of "minor performer in a play" (1777) and "special edition of a newspaper" (1793) -- all probably are from shortenings of extraordinary, which was used extensively in 18c. as noun and adverb in places we would use extra today.
extra-: only recorded in classical Latin in extraordinarius, but much used in Medieval Latin and modern formations; it represents Latin extra (adv.) "on the outside, without, except," the old fem. ablative singular of exterus "outward, outside," comparative of ex "out of" (see ex-).
extra-special (adj.): 1889, from extra + special. Originally of certain editions of daily newspapers.
extract (v.): late 15c., from Latin extractus, past participle of extrahere "draw out," from ex- "out" (see ex-) + trahere "to draw" (see tract (n.1)). Related: Extracted; extracting.
extract (n.): mid-15c., from Late Latin extractum, noun use of neuter past participle of extrahere "to draw out" (see extract (v.)).
extraction (n.): early 15c., from Old French estraction (12c.) or directly from Medieval Latin extractionem (nominative extractio), noun of action from past participle stem of Latin extrahere (see extract (v.)).
extracurricular (adj.): 1925, from extra- + curricular (see curriculum).
extradite (v.): 1864, back-formation from extradition. Related: Extradited; extraditing.
extradition (n.): 1833, from French extradition (18c.), apparently a coinage of Voltaire's, from Latin ex "out" (see ex-) + traditionem (nominative traditio) "a delivering up, handing over," noun of action from tradere "to hand over" (see tradition).
This word might be adopted in our language with advantage, as we have none which conveys the same meaning. Extradition signifies the delivering up of criminals who may have sought refuge in any country, to the government whose subjects they are, on a claim being made to this effect. [from a footnote to the word extradition in translation of "Memoirs of Marshal Ney," London, 1833]
extrajudicial (adj.): also extra-judicial, 1580s (implied in extrajudicially); see extra- + judicial.
extramarital (adj.): by 1844, from extra- + marital.
extraneous (adj.): 1630s, from Latin extraneus "external, strange," from extra "outside of" (see extra-).
extraordinaire (adj.): 1940, from French extraordinaire (14c.), literally "extraordinary, unusual, out of the ordinary," but used colloquially as a superlative; see extraordinary.
extraordinary (adj.): early 15c., from Latin extraordinarius "out of the common order," from extra ordinem "out of order," especially the usual order, from extra "out" (see extra-) + ordinem (nominative ordo) "order" (see order). Related: Extraordinarily.
extrapolate (v.): 1874, a back-formation from extrapolation by analogy of interpolate. Said in early references to be an expression of Sir George Airy (1801-1892), English mathematician and astronomer. Related: Extrapolated; extrapolating.
extrapolation (n.): by 1867, from extra- + back half of interpolation; original sense was "insert intermediate terms in a mathematical series." Transferred sense of "drawing a conclusion about the future based on present tendencies" is from 1889. Cf. extrapolate.
extrasensory (adj.): also extra-sensory, 1934, coined as part of extra-sensory perception in J.B. Rhine's work, from extra- + sensory.
extraterrestrial (adj.): also extra-terrestrial, 1812, from extra- + terrestrial. As a noun from 1956.
extraterritoriality (n.): also extra-territoriality, 1803, from extraterritorial (from extra- + territorial) + -ity.
extravagance (n.): 1640s, from French extravagance, from Late Latin extravagantem (see extravagant). Specifically of wasteful spending from 1727. Extravagancy is attested from c.1600.
extravagant (adj.): late 14c., from Medieval Latin extravagantem, originally a word in Canon Law for uncodified papal decrees, present participle of extravagari "wander outside or beyond," from Latin extra "outside of" (see extra-) + vagari "wander, roam" (see vague). Extended sense of "excessive, extreme" first recorded 1590s; that of "wasteful, lavish" 1711. Related: Extravagantly.
extravaganza (n.): 1754, with reference to peculiar behavior, 1794 of a fantastic type of performance or writing, from Italian extravaganza, literally "an extravagance," from estravagante, from Medieval Latin extravagantem (see extravagant).
extravasation (n.): 1670s, from Latin extra "outside" (see extra-) + form derived from vas "vessel." Related: Extravasate (1660s).
extraversion (n.): 1690s, "a turning out," from Medieval Latin extraversionem, from extra "outward" (see extra-) + versionem (see version). Psychological sense is from 1915; see extraverted.
extraverted (adj.): in modern psychology, 1915, a variant of extroverted (see extrovert). Related: Extravert (n.), for which also see extrovert. There was a verb extravert in mid- to late 17c. meaning "to turn outward so as to be visible," from Latin extra "outward" + vertere "to turn."
extreme (adj.): early 15c., from Old French extreme (13c.), from Latin extremus "outermost, utmost, farthest, last," superlative of exterus (see exterior).

In English as in Latin, not always felt as a superlative, hence more extreme, most extreme (which were condemned by Johnson). The noun is first recorded 1540s, originally of the end of life, cf. Latin in extremis. Extreme unction preserves the sense of "last, latest" (15c.). Extremes "opposite ends of anything" is from 1550s.
extremely (adv.): 1530s, from extreme + -ly (2). Originally "with great severity," later more loosely, "in extreme degree" (1570s).
extremism (n.): 1848, from extreme + -ism.
I would remind you that extremism in the defense of liberty is no vice! And let me remind you also that moderation in the pursuit of justice is no virtue. [Barry Goldwater (1909-1998), acceptance speech as Republican candidate for President, 1963]
extremist (n.): 1840, from extreme + -ist.
extremities (n.): "hands and feet," uttermost parts of the body, early 15c., plural of extremity. Meaning "a person's last moments" is from c.1600.
extremity (n.): late 14c., from Old French estremite (13c.), from Latin extremitatem (nominative extremitas) "the end of a thing," from extremus; see extreme, the etymological sense of which is better preserved in this word.
extricable (adj.): 1620s, from extricate + -able. Related: Extricably.