Online Etymology Dictionary

delve: O.E. delfan "to dig" (class III strong verb; past tense dealf, pp. dolfen), common W.Gmc. verb with cognates in Slavic. Weak inflections emerged 14c.-16c.
dem: representing pronunciation of them in Jamaican speech, from 1868. As a minced form of damn, attested from late 14c.
demagogue: 1640s, from Gk. demagogos "leader of the people," from demos "people" (see demotic) + agogos "leader," from agein "to lead" (see act). A term of disparagement ever since it was first used in Athens, 5c. B.C.E. As a verb, attested by 1980s, Amer.Eng. Related: Demagogic (1831); demagoguery (1866); demagogy (1650s).
demand: late 13c., from O.Fr. demander "to request," from L. demandare "entrust, charge with a commission," from de- "completely" + mandare "to order." The political economy sense (correlating to supply) is first attested 1776 in Adam Smith.
demarcate: 1816, back-formation from demarcation. Related: Demarcated (1882); demarcating (1840).
demarcation: c.1752, from Sp. linea de demarcacion, or Port. linha de demarcaçao, line laid down by the Pope, May 4, 1493, dividing the New World between Spain and Portugal on a line 100 leagues west of the Cape Verde Islands. Applied from 1801 to other lines dividing regions.
demarche: 1650s, "walk, step," from Fr. démarche (15c.), from démarcher (12c.) "to march," from de- + marcher (see march (v.)). Meaning "a diplomatic step" attested from 1670s. A word never quite anglicized.
demark: 1650s, abstracted from demarcation by infl. of mark.
demean: "lower in dignity," c.1600, perhaps from de- "down" + mean (adj.) and modeled on debase. Indistinguishable in some uses from obsolete demean (see demeanor) which influenced it and may be its true source.
demeaning: 1880, pp. adj. from demean.
demeanor: late 15c., from obsolete M.E. demean "behave in a certain way" (early 14c.), from O.Fr. demener, from de- "completely" + mener "to lead, direct," from L. minare "to threaten," in L.L. "to drive (a herd of animals)." Sense in English evolved from notion of "conduct, manage" (oneself).
demeanour: British spelling of demeanor (q.v.); for suffix, see -or.
dement: 1540s, "to drive mad," probably from M.Fr. dementer, from L.L. dementare "out of one's mind," from phrase de mente, from de + mente, ablative of mens mind" (see mind (n.)).
demented: 1640s, from obsolete dement "drive mad."
dementia: 1806, L. noun of state from dementem, from dementer (see dement). It existed earlier in an anglicized form, demency (1520s), from Fr. démence. Dementia præcox is a Mod.L. form recorded from 1899 in Eng., 1891 in Ger., from Fr. démence précoce (1857). See precocious.
demerit: 1399, from O.Fr. desmerite, from des- "not, opposite" + merite "merit." L. demereri meant "to merit, deserve," from de- in its completive sense. But M.L. demeritum meant "fault." Both senses existed in the M.Fr. form of the word. Meaning "penalty point in school" is attested from 1862.
Demerol: trademark name, by 1942; originally a morphine substitute.
demesne: late 13c., from O.Fr. demeine, from L. dominicus "belonging to a master," from dominus "lord." Re-spelled by Anglo-Fr. legal scribes under infl. of O.Fr. mesnie "household" (and the concept of a demesne as "land attached to a mansion") and their fondness for inserting -s- before -n-. Essentially the same word as domain.
Demeter: Gk. Damater, lit. "Earth-Mother," from da, Doric form of Gk. ge "earth" + mater. The name Demetrius means "son of Demeter."
demi-: early 15c., from O.Fr. demi "half," from L.L. dimedius, from L. dimidius, from dis- "apart" + medius "middle" (see medial).
demi-monde: 1855, also demimonde, from Fr. demi-monde "so-so society," lit. "half-world," from demi- "half" + monde, from L. mundus "world" (see mundane). Popularized by use in title of a comedy by Alexandre Dumas fils (1824–1895). Dumas' Demi-Monde "is the link between good and bad society ... the world of compromised women, a social limbo, the inmates of which ... are perpetually struggling to emerge into the paradise of honest and respectable ladies" ["Fraser's Magazine," 1855]. Not properly used of courtesans. Eighteenth-century English demi-rep (1749, the second element short for reputation) was defined as "a woman that intrigues with every man she likes, under the name and appearance of virtue ... in short, whom every body knows to be what no body calls her" [Fielding].
demi-tasse: also demitasse, 1842, from Fr., lit. "half-cup," from demi- + tasse, an O.Fr. borrowing from Arabic tassah, from Pers. tasht "cup, saucer" (cf. It. tazza, Sp. taza "cup").
demigod: 1530, from demi- + god, rendering L. semideus. The child of sexual intercourse between a deity and a mortal, a man raised to divine rank, or a minor god.
demijohn: 1769, partial translation and word-play from Fr. damejeanne (1694) "Lady Jane," term used for large globular wicker-wrapped bottle, perhaps because its shape suggested a stout woman in the costume of the period. A general Mediterranean word, with forms found in Sp., Port., It., and Ar.
demilitarize: 1883, in reference to the Austrian military frontier in the Balkans.
demilitarized zone: attested by 1921 (the Versailles Treaty uses neutralized zone).
demise: 1442, from M.Fr. demise, fem. pp. of demettre "dismiss, put away," from des- "away" (from L. dis-) + M.Fr. mettre "put," from L. mittere "let go, send." Originally "transfer of estate by will," meaning extended 1754 to "death" because that's when this happens.
demit: 1610s (figurative), 1640s (literal), from L. demittere "to send down," from de- + mittere "to send" (see mission).
demiurge: 1678, from Latinized form of Gk. demiourgos, lit. "public or skilled worker" (from demos "common people" + ergos "work"). The title of a magistrate in some Gk. city-states and the Achæan League; taken in Platonic philosophy as a name for the maker of the world. In the Gnostic system, "conceived as a being subordinate to the Supreme Being, and sometimes as the author of evil" [OED].
demo: short for demonstration (tape, disc, etc.). Music recording given out for promotional purposes, 1963. The word was earlier used to mean public political demonstrations (1936).
demob (v.): 1920, short for demobilize. Originally in reference to World War I troops returning to civilian life.
demobilize: 1882, from de- + mobilize. Related: Demobilization (1866).
democracy: 1570s, from M.Fr. democratie, from M.L. democratia (13c.), from Gk. demokratia, from demos "common people," originally "district" (see demotic), + kratos "rule, strength" (see -cracy).
democrat: 1790, "adherent of democracy," with reference to France; revived in U.S. politics 1798, with a capital D.
democratic: c.1600, from Fr. democratique, from M.L. democraticus, from Gk. demokratikos, from demokratia (see democracy). Earlier was democratian (1570s). U.S. political usage (with a capital D) attested from 1800. The party originally was the Anti-Federal party, then the Democratic-Republican (Democratic for short). It formed among those opposed to extensive powers for the U.S. federal government. The name of the party was not formally shortened to Democratic until 1829. Colloquial abbreviation Demo dates to 1793. Democratic socialism is attested from 1849.
democratic party: 1790 in reference to France, c.1800 in U.S.; see democratic.
democratize: 1798 (trans.), 1840 (intrans.), from Fr. democratiser (see democracy). Related: Democratization (1865).
demographic: 1982, from demographics.
demographics: 1967, the science of divining from demographic statistics, from demography + -ics. Originally in reference to TV audiences and advertisers.
demography: 1880, from Gk. demos "people" (see demotic) + English -graphy "the study of," from Gk. -graphia "description," from graphein "to write" (about).
demolish: 1560s, from M.Fr. demoliss-, stem of demolir "to destroy, tear down" (late 14c.), from L. demoliri "tear down," from de- "down" + moliri "build, construct," from moles (gen. molis) "massive structure."
demolition: 1540s, from Fr. démolition (14c.), from L. demolitionem, noun of action from demoliri (see demolish). Mencken noted demolition engineer for "house-wrecker" by 1936. Demolition derby is recorded from 1956, Amer.Eng., defined by OED as "a contest in which old cars are battered into one another, the last one running being declared the winner."
demon: late 14c., from L. dæmon "spirit," from Gk. daimon (gen. daimonos) "lesser god, guiding spirit, tutelary deity," (sometimes including souls of the dead), used (with daimonion) in Christian Gk. translations and Vulgate for "god of the heathen" and "unclean spirit." Jewish authors earlier had employed the Gk. word in this sense, using it to render shedim "lords, idols" in the Septuagint, and Matt. viii.31 has daimones, translated as deofol in O.E., feend or deuil in M.E. The original mythological sense is sometimes written dæmon for purposes of distinction. The Demon of Socrates (late 14c.) was a daimonion, a "divine principle or inward oracle." His accusers, and later the Church Fathers, however, represented this otherwise. Fem. form demoness first attested 1630s. The Demon Star (1895) is Algol.
demoniac: late 14c., from L.L. dæmoniacus (c.200), from Gk. daimonion, from daimon (see demon).
demonic: 1660s, from L. dæmonicus, from Gk. daimonikos "pertaining to a demon, possessed by a demon," from daimon (see demon).
demonize: 1821, "to make into a demon" (literally or figuratively), from M.L. dæmonizare, from Gk. daimonizesthai "to be possessed by a demon;" from daimon (see demon). Related: Demonizing (1857).
demonstrable: c.1400, from L. demonstrabilis, from demonstrare (see demonstration). Related: Demonstrably (1640s).
demonstrate: 1550s, "to point out," from L. demonstrat-, pp. stem of demonstrare (see demonstration). Meaning "to point out by argument or deduction" is from 1570s. Related: Demonstrated (1670s).
demonstration: late 14c., from L. demonstrationem, from demonstrare, from de- "entirely" + monstrare "to point out, show," from monstrum "divine omen, wonder." Meaning "public show of feeling," usually with a mass meeting and a procession, is from 1839.
demonstrative: late 14c., "that shows something," from Fr. démonstratif (14c.), from L. demonstrativus, from pp. stem of demonstrare (see demonstration). Meaning "given to outward expressions of feelings" is from 1819. Demonstrative pronoun is late 16c.