Online Etymology Dictionary

dudgeon (n.): 1570s, duggin, of unknown origin. One suggestion is Italian aduggiare "to overshadow," giving it the same sense development as umbrage. No clear connection to earlier dudgeon (late 14c.), a kind of wood used for knife handles, which is perhaps from a French word.
duds (n.): c. 1300, dudde "cloak, mantle," later in plural, "ragged clothing" (1560s), of uncertain origin.
due (adj.): early 14c., "customary, regular;" mid-14c., "owing, payable," from Old French deu, past participle of devoir "to owe," from Latin debere "to owe" (see debt).

In reference to points of the compass (as in due east) it is attested from c. 1600, originally nautical, from notion of "fitting, rightful." As an adverb from 1590s; as a noun from early 15c. Prepositional phrase due to (much maligned by grammarians) is from 1897.
duel (n.): 1590s (from late 13c. in Latin form), from Medieval Latin duellum "combat between two persons," by association with Latin duo "two," but originally from Latin duellum "war," an Old Latin form of bellum (see bellicose). Retained in poetic and archaic language and apparently given a special meaning in Medieval or Late Latin of "one-on-one combat" on fancied connection with duo "two."
duel (v.): 1640s, see duel (n.). Related: Dueled; dueling; duelling.
duelist (n.): 1590s, from duel + -ist.
duenna (n.): 1660s, "chief lady in waiting upon the queen of Spain," also "an elderly woman in charge of girls from a Spanish family," from Spanish dueña "married lady, mistress" (fem. of dueño "master"), from Latin domina (see dame). Sense extended in English to "any elderly woman chaperon of a younger woman" (1708).
dues (n.): "fee for membership," 1660s, from plural of due (n.). To pay (one's) dues in the figurative sense is from 1943. "Giue them their due though they were diuels" [1589].
duet (n.): 1740, from French duet, from Italian duetto "short musical composition for two voices," diminutive of duo "two" (see two). As a verb, from 1822. The Italian form of the noun was used in English from c. 1724.
duff (n.): "buttocks, rump," 1830s, of unknown origin.
duffel: see duffle.
duffer (n.): "inept person; old man," especially "bad golfer," 1842, perhaps from Scottish duffar "dull or stupid person," from dowf "stupid," literally "deaf," from Old Norse daufr, with pejorative suffix -art. Or perhaps from 18c. thieves' slang duff (v.) "to dress or manipulate an old thing and make it look new."
duffle (n.): 1670s, from Dutch duffel, from Duffel, town in Brabant where the cloth was originally sold. Duffel bag is American English, first recorded 1917 in a letter of e e cummings.
dufus (n.): see doofus.
dug (n.): "animal nipple," or, contemptuously, "the human female breast," 1520s, origin obscure, related to Swedish dagga, Danish dægge "to suckle."
dug (v.): past tense and past participle of dig (v.).
Dugan: from Irish Dubhagan, diminutive of dubh "black."
dugong (n.): 1800, from Malay duyung, which is dugung in the Philippines.
dugout (n.): also dug-out, "canoe," 1722, American English, from dug, past participle of dig (v.) + out (adv.). Baseball sense is first recorded 1914, from c. 1855 meaning of "rough shelter."
duke (n.): early 12c., "sovereign prince," from Old French duc (12c.) and directly from Latin dux (genitive ducis) "leader, commander," in Late Latin "governor of a province," from ducere "to lead," from PIE *deuk- "to lead" (source also of Old English togian "to pull, drag," Old High German ziohan "to pull," Old English togian "to draw, drag," Middle Welsh dygaf "I draw").

Applied in English to "nobleman of the highest rank" probably first mid-14c., ousting native earl. Also used to translate various European titles (such as Russian knyaz).
dukes (n.): "hands," 1874, now mainly in put up your dukes (phrase from 1859), probably not connected to duke (n.). Chapman ["Dictionary of American Slang"] suggests Romany dook "the hand as read in palmistry, one's fate;" but Partridge ["Slang To-day and Yesterday"] gives it a plausible, if elaborate, etymology as a contraction of Duke of Yorks, rhyming slang for forks, a Cockney term for "fingers," thus "hands."
dulcet (adj.): late 14c., from Old French doucet, diminutive of doux "sweet," earlier dulz, from Latin dulcis, from PIE *dlk-wi-, suffixed form of root *dlk-u- "sweet" (compare glucose).
dulcimer (n.): late 15c., from Middle French doulce mer, variant of doulcemele, perhaps from doulz de mer, said to represent Latin dulce "sweet" + melos "song," from Greek melos "melody."
Dulcinea: "sweetheart," 1748, from the name of Don Quixote's mistress in Cervantes' romance, the name a Spanish fem. derivative of Latin dulce "sweet."
dull (adj.): c. 1200, "stupid;" early 13c., "blunt, not sharp;" rare before mid-14c., apparently from Old English dol "dull-witted, foolish," or an unrecorded parallel word, or from Middle Low German dul "slow-witted," both from Proto-Germanic *dulaz (source also of Old Frisian and Old Saxon dol "foolish," Old High German tol, German toll "mad, wild," Gothic dwals "foolish"), from PIE *dheu- (1) "dust, vapor, smoke" (and related notions of "defective perception or wits"). Of color from early 15c.; of pain or other sensations from 1725. Sense of "boring" first recorded 1580s.
dull. (8) Not exhilarating; not delightful; as to make dictionaries is dull work. [Johnson]
Dullsville, slang for "town where nothing happens," attested from 1960.
dull (v.): c. 1200, "to grow weary, tire;" of pointed or edged things from c. 1400; of the senses from 1550s; from dull (adj.). Related: Dulled; dulling.
dullard (n.): mid-15c. (but early 13c. as a surname), from dull (adj.) + -ard.
Duluth: city in Minnesota, U.S., named for French pioneer explorer Daniel Greysolon, sieur du Luth (1649-1710), "the Robin Hood of Canada," the leader of the coureurs de bois, who passed through in 1678 on a mission into the wilderness.
duly (adj.): late 14c., duweliche "rightly, properly," from dewe "due" (see due) + -liche (see -ly (2)).
duma (n.): Russian national assembly, 1870 (in reference to city councils; the national one was set up in 1905), literally "thought," from a Germanic source (compare Gothic doms "judgment," English doom, deem).
dumb (adj.): Old English dumb "silent, unable to speak," from PIE *dheubh- "confusion, stupefaction, dizziness," from root *dheu- (1) "dust, mist, vapor, smoke," and related notions of "defective perception or wits."

The Old English, Old Saxon (dumb), Gothic (dumbs), and Old Norse (dumbr) forms of the word meant only "mute, speechless;" in Old High German (thumb) it meant both this and "stupid," and in Modern German this latter became the only sense. Meaning "foolish, ignorant" was occasionally in Middle English, but modern use (1823) comes from influence of German dumm. Related: dumber; dumbest.

Applied to silent contrivances, hence dumbwaiter. As a verb, in late Old English, "to become mute;" c. 1600, "to make mute." To dumb (something) down is from 1933.
dumbass (n.): by 1959, from dumb "stupid" + ass (n.2).
dumbbell (n.): "weighted bar used for exercise," 1711, originally an apparatus like that used to ring a church bell, but without the bell (hence dumb); used for exercise but sometimes also to practice ringing changes. Figurative sense of "blockhead, stupid person" attested by 1918, American English college slang.
dumbfound (v.): 1650s, from dumb (adj.) + ending from confound.
dumbfounded (adj.): past participle adjective from dumbfound.
dumbledore (n.): 1787, noted as a dialect word in Hampshire, Cornwall, etc. for "a bumblebee."
dumbstruck (adj.): 1823, from dumb + past participle of strike (v.).
dumbwaiter (n.): 1749, an article of furniture, from dumb (adj.) + waiter (apparently because it serves as a waiter but is silent). As a movable platform for passing dishes, etc., up and down from one room (especially a basement kitchen) to another, from 1847.
dumdum bullet: 1897, named for Dum-Dum arsenal in Bengal, where the British made them to use against fanatical charges by tribesmen. Outlawed by international declaration, 1899. The place name is literally "hill, mound, battery," cognate with Persian damdama.
dummkopf (n.): 1809 (dom cop), from German dummkopf, literally "dumb head;" see dumb (adj.) + cup (n.).
dummy (n.): 1590s, "mute person," from dumb (adj.) + -y (3). Extended by 1845 to "figure representing a person." Used in card games (originally whist) since 1736. Meaning "dolt, blockhead" is from 1796.
dump (v.): early 14c., "throw down or fall with force," perhaps from a Scandinavian source (compare Danish dumpe, Norwegian dumpa "to fall suddenly"). The sense of "unload en masse" is first recorded in American English 1784. That of "discard, abandon" is from 1919. Related: Dumped; dumping. Dump truck is from 1930.
dump (n.): "place where refuse is dumped," 1865, originally of mining operations, from dump (v.). Meaning "any shabby place" is from 1899. Meaning "act of defecating" is from 1942.
dumpling (n.): c. 1600, Norfolk dialect, of uncertain origin, perhaps from some Low German word or from noun dump "lump" (late 18c.). Related: Dumplings.
dumps (n.): "low spirits," 1520s, plural of dumpe "a fit of musing," possibly from Dutch domp "haze, mist," from Middle Dutch damp "vapor" (see damp (n.)).
Dumpster (n.): 1930s, from Dempster-Dumpster trash-hauling mechanism, patented by Dempster Brothers and probably named from dump (v.) with the surname in mind. Dumpster diving attested from 1979.
dumpy (adj.): "short and stout," 1750, apparently from some noun dump (compare dumpling), but the connection is unclear.
dun (v.): "to insist on payment of debt," 1620s, perhaps related to dunnen "to sound, resound, make a din" (c. 1200, dialectal variant of din), or shortened from dunkirk (c. 1600) "privateer," a private vessel licensed to attack enemy ships during wartime, from Dunkirk, French port from which they sailed. The oldest theory traces it to a Joe Dun, supposedly a London bailiff famous for catching defaulters. Related: Dunned; dunning. As a noun from 1620s.
dun (adj.): Old English dunn "dingy brown, dark-colored," perhaps from Celtic (compare Old Irish donn "dark;" Gaelic donn "brown, dark;" Welsh dwnn "brownish"), from PIE *donnos, *dusnos "dark."
Duncan: from Gaelic donn "brown, dark" (see dun (adj.)) + ceann "head."