Online Etymology Dictionary

dialysis: 1586, from Gk. dialysis "dissolution, separation," from dialyein "dissolve, separate," from dia- "apart" + lyein "loosen" (see lose). Used originally in logic and grammar; chemistry sense is first recorded 1861, medicine 1914.
diamante: 1904, from Fr. diamanté, pp. of diamanter "to set with diamonds," from O.Fr. diamant (see diamond).
diameter: late 14c., from O.Fr. diametre, from L. diametrus, from Gk. diametros "diagonal of a circle," from dia- "across, through" + metron "a measure" (see meter (2)).
diametric: 1868, from Gk. diametrikos, from diametros (see diameter). Related: Diametrical.
diametrically: 1630s, "completely" (opposed, contrary, etc.), from diametric (q.v.). Mostly in figurative use; the two points that mark the ends of a line of diameter across a circle are opposite one another.
diamond: early 14c., from O.Fr. diamant, from M.L. diamantem (nom. diamas), from V.L. *adiamantem (altered by infl. of the many Gk. words in dia-), from L. adamantem (nom. adamans) "the hardest metal," later, "diamond" (see adamant). Playing card suit is from 1590s; Sense in baseball is Amer.Eng. 1875.
Diana: c.1200, ancient It. goddess, patroness of virginity and hunting, later identified with Gk. Artemis, and through her with eastern goddesses such as Diana of Ephesus.
dianetics: 1950, coined by U.S. writer L. Ron Hubbard, an alteration of dianoetic (1677) "of or pertaining to thought," from Gk. dianoetikos, from dianoetos, verbal adj. from dianoe-esthai "to think," from dia- "through" + noe-ein "to think, suppose."
diaper: early 14c., from O.Fr. diapre "ornamental cloth," from M.L. diasprum, from Medieval Gk. diaspros, from dia- "entirely, very" + aspros "white." Aspros originally meant "rough," and was applied to the raised parts of coins (among other things), and thus was used in Byzantine Gk. to mean "silver coin," from which the bright, shiny qualities made it an adj. for "whiteness." Modern sense of "underpants for babies" is continuous since 1837, but such usage has been traced back to 1590s.
diaphanous: 1614, from M.L. diaphanus, from Gk. diaphanes, from dia- "through" + phainesthai, middle voice form (subject acting on itself) of phainein "to show" (see phantasm).
diaphragm: late 14c., from L.L. diaphragma, from Gk. diaphragma (gen. diaphragmatos) "partition, barrier," from diaphrassein "to barricade," from dia- "across" + phrassein "to fence or hedge in." The native word is midriff. Meaning "contraceptive cap" is from 1933.
diarize: 1842, from diary + -ize.
diarrhea: late 14c., from O.Fr. diarrie, from L. diarrhoea, from Gk. diarrhoia "diarrhea" (coined by Hippocrates), lit. "a flowing through," from diarrhein "to flow through," from dia- "through" + rhein "to flow" (see rheum). Respelled 16c. from diarria on Latin model.
diarrhoea: variant spelling of diarrhea (q.v.); see also oe.
diary: 1581, from L. diarium, "daily allowance," later "a journal," neut. of diarius "daily," from dies "day." Earliest sense was a daily record of events; sense of the book in which such are written is first attested in Ben Jonson's "Volpone" (1605).
diaspora: coined 1876 from Gk. diaspora, from diaspeirein "to scatter about, disperse," from dia- "about, across" + speirein "to scatter" (see sprout). Originally in Deut. xxviii.25. Related: Diasporic.
diatessaron: late 14c. as a term in music meaning "interval of a fourth;" 1803 in reference to harmonizings of the gospels, especially that of Tatian (2c.), from Gk. dia tessaron, from dia "composed of" (lit. "through") + tessaron "four."
diatom: 1845, coined from Gk. diatomos "cut in two," from diatemnein "to cut through," from dia- "through" + temnein "to cut." So called because they typically appear to have been cut in half. Related: Diatomic.
diatribe: 1580s, from L. diatriba "learned discussion," from Gk. diatribe "discourse, study," lit. "a wearing away (of time)," from dia- "away" + tribein "to wear, rub," from PIE base *ter- "to rub, turn, twist" (see throw). Sense of "invective" is 1804, apparently from French.
Diazepam: 1961, from (benzo)diazep(ine) + -pam, apparently an arbitrary suffix.
dib: see dibs.
dibble: "to make a hole in the soil (as to plant seeds)," 1580s, probably from M.E. dibben, probably akin to dip. The noun meaning a tool to do this is attested from mid-15c.
dibs: children's word to express a claim on something, 1932, originally U.S., apparently a contraction of dibstone "a knucklebone or jack in a children's game" (1690s), of unknown origin.
dice: early 14c., des, dys, plural of dy (see die (n.)), altered 14c. to dyse, dyce, and 15c. to dice. "As in pence, the plural s retains its original breath sound, probably because these words were not felt as ordinary plurals, but as collective words" [OED]. Sometimes used as singular 1400-1700. The verb "to cut into cubes" is first recorded late 14c. Related: Diced.
dicey: "risky, uncertain" (as the roll of dice), 1940s, aviators' jargon, from dice + -y (2).
dichotomy: 1610, from Gk. dichotomia "a cutting in half," from dicha "in two" + temnein "to cut" (see tome).
dick: "fellow, lad, man," 1553, rhyming nickname for Rick, short for Richard, one of the commonest Eng. names, it has long been a synonym for "fellow," and so most of the slang senses are probably very old, but naturally hard to find in the surviving records. The meaning "penis" is attested from 1891 in British army slang. Meaning "detective" is recorded from 1908, perhaps as a shortened variant of detective.
Dick Whittington: The story is an old one, told under other names throughout Europe, of a poor boy who sends a cat he had bought for a penny as his stake in a trading voyage; the captain sells it on his behalf for a fortune to a foreign king whose palace is overrun by rats. The hero devotes part of his windfall to charity, which may be why the legend attached in England since 16c. to Sir Richard Whittington (d.1423), three times Lord Mayor of London, who died childless and devoted large sums in his will to churches, almshouses, and St. Bartholomew's Hospital.
dickens: exclamation, 1598, probably altered from Dickon, nickname for Richard and source of the surnames Dickens and Dickenson, but exact derivation and meaning are unknown.
dicker (v.): "haggle, bargain in a petty way," 1802, Amer.Eng., perhaps from dicker (n.) "a unit or package of tens," especially hides (attested from c.1275), probably from L. decuria "parcel of ten" (supposedly a unit of barter on the Roman frontier), from decem "ten" (see ten).
dickhead: "stupid, contemptible person," by 1969, from dick in the "penis" sense + head.
dicky: "detached shirt front," 1811; "a small bird," 1851; dim. of dick, but the applications are obscure in both cases.
Dictaphone: trademarked by the Columbia Graphophone Company in 1907; from dictation + -phone. A separate company from 1923.
dictate (v.): 1590s, "to practice dictation," from L. dictatus, pp. of dictare "say often, prescribe," frequentative of dicere "tell, say" (see diction). Sense of "command" is 1620s. The noun is from 1590s. Related: Dictated; dictates; dictating.
dictation: 1727, from L.L. dictationem, noun of action from dictare (see dictate).
dictator: late 14c., from L. dictator, agent noun from dictare (see dictate). Transf. sense of "one who has absolute power or authority" in any sphere is from c.1600. In Latin use, a dictator was a judge in the Roman republic temporarily invested with absolute power.
dictatorial: 1701, from dictator.
dictatorship: 1580s, from dictator + -ship.
diction: 1540s, from L.L. dictionem (nom. dictio), from L. "a saying, expression, word," from dic-, stem of dicere "speak, tell, say," related to dicare "proclaim, dedicate," from PIE base *deik- "to point out" (cf. Skt. dic- "point out, show," Gk. deiknynai "to prove," O.H.G. zeigon, Ger. zeigen "to show," O.E. teon "to accuse," tæcan "to teach").
dictionary: 1520s, from M.L. dictionarium "collection of words and phrases," from L. dictionarius "of words," from dictio "word." Probably first Eng. use in title of a book was in Sir Thomas Elyot's "Latin Dictionary" (1538) though L. Dictionarius was so used from early 13c.
Dictograph: patented 1907 in U.S. by K.M. Turner and W. Donnan, from dictation + -graph.
dictum: 1670, from L. dictum "thing said," neut. of dictus, pp. of dicere "say" (see diction). In legal use, a judge's expression of opinion which is not the formal resolution of a case.
did: p.t. of do (q.v.).
didactic: 1650s, from Fr. didactique, from Gk. didaktikos "apt at teaching," from didaktos "taught," from didaskein "teach," from PIE base *dens- "wisdom, to teach, learn." Related: Didactically; didacticism.
diddle: "to cheat, swindle," 1806, from dial. duddle, diddle "to totter" (1632). Meaning "waste time" is recorded from 1825. Meaning "to have sex with" is from 1879; that of "to masturbate" (especially of women) is from 1950s. More or less unrelated meanings that have gathered around a suggestive sound.
didgeridoo: 1924, Australian, of imitative origin.
didn't: by 1775, contraction of did not.
dido: "prank, caper," 1807, Amer.Eng. slang, perhaps from the queen in the "Aeneid." Usually in phrase to cut didoes.
didst: archaic 2nd pers. sing. past indic. of do (q.v.).
die (v.): mid-12c., possibly from O.Dan. døja or O.N. deyja "to die, pass away," both from P.Gmc. *dawjanan, from PIE base *dheu- "to pass away, become senseless." It has been speculated that O.E. had *diegan, from the same source, but it is not in any of the surviving texts and the preferred words were steorfan (see starve), sweltan (see swelter), wesan dead, also forðgan and other euphemisms. Languages usually don't borrow words from abroad for central life experiences, but "die" words are an exception, since they are often hidden or changed euphemistically out of superstitious dread. A Du. euphemism translates as "to give the pipe to Maarten." Regularly spelled dege through 15c., and still pronounced "dee" by some in Lancashire and Scotland. Used figuratively (of sounds, etc.) from 1580s. Related: Died; dies.