Online Etymology Dictionary

euphemism: 1656, from Gk. euphemismos "use of a favorable word in place of an inauspicious one," from euphemizein "speak with fair words," from eu- "good" + pheme "speaking," from phanai "speak" (see fame). In ancient Greece, the superstitious avoidance of words of ill-omen during religious ceremonies, or substitutions such as Eumenides "the Gracious Ones" for the Furies (see also Euxine). In Eng., a rhetorical term at first; broader sense of "choosing a less distasteful word or phrase than the one meant" is first attested 1793.
decease: early 14c., from Fr. deces, from L. decessus "death," lit. "departure" (euphemism for mors), from pp. stem of decedere "die," lit. "to go down, depart," from de- "away" + cedere "go" (see cede). Still used with a tinge of euphemism.
Sam Hill: euphemism for "Hell," 1839, Amer.Eng., of unknown origin.
obituary: 1706, "register of deaths," from M.L. obituarius "a record of the death of a person," lit. "pertaining to death," from L. obitus "departure, a going to meet, encounter" (a euphemism for "death"), from stem of obire "go to meet" (as in mortem obire "meet death"), from ob "to, toward" + ire "go." Meaning "record or announcement of a death, esp. in a newspaper, and including a brief biographical sketch" is from 1738. A similar euphemism is in O.E. cognate forðfaran "to die," lit. "to go forth."
crikey: euphemism for Christ, first recorded 1838.
bally: 1885, British, euphemism for bloody.
dang: 1793, euphemism for damn.
intimacy: 1640s, from intimate. As a euphemism for "sexual intercourse," from 1670s.
cohabit (v.): euphemism since c.1530 to describe a couple living together without benefit of marriage (see habitation).
frig: "to move about restlessly," c.1460, perhaps a variant of frisk (q.v.). As a euphemism for "to fuck" or "to masturbate" it dates from 1598.
collateral damage: by 1873 in legal cases; in modern use, generally a euphemism for "the coincidental killing of civilians," U.S. coinage, c.1968, at first generally with ref. to nuclear weapons.
deprived: 1550s, "dispossessed," pp. adj. from deprive. As a euphemism for the condition of children who lack a stable home life, by 1945.
poop (n.2): "excrement," 1744, a children's euphemism, probably of imitative origin; cf. the same word in the sense "to break wind softly," attested from 1721, earlier "to make a short blast on a horn" (late 14c.).
golly: euphemism for God, first recorded 1775, in a source that refers to it as "a sort of jolly kind of oath, or asseveration much in use among our carters, & the lowest people."
jumble (v.): 1529, originally "to move confusedly," perhaps coined on model of stumble, tumble, etc. In 17c., it was yet another euphemism for "have sex with" (a sense first attested 1582). The noun meaning "a confused mixture" is from 1661.
skulduggery: 1856, apparently an alteration of Scottish sculdudrie "adultery" (1713), sculduddery "bawdry, obscenity" (1821), a euphemism of uncertain origin.
caramba: exclamation of dismay or surprise, 1835, from Sp., said to be a euphemism for carajo "penis," from V.L. *caraculum "little arrow."
blooming: late 14c., from bloom. Meaning "full-blown" (often a euphemism for bloody) is attested from 1882.
shift (n.2): "body garment, underclothing," 1598, originally used of both men's and women's. In 17c., it began to be used as a euphemism for smock, and was itself displaced, for similar reasons of delicacy, in 19c. by chemise.
overseas: 1583, from over + sea. Popularized WWI as a British euphemism for "colonial."
bathroom: 1780, from bath + room. Originally a room with apparatus for bathing, used 20c. in U.S. as a euphemism for a lavatory and often noted as a word that confused British travelers.
adult (adj.): 1530s (but not common until mid-17c.), from L. adultus "grown up," pp. of adolescere "grow up, mature" (see adolescent). As a euphemism for "pornographic," it dates to 1958 and does no honor to the word. The noun meaning "adult person" is from 1650s.
sanitation: 1848, irregularly formed from sanitary. As a euphemism for garbage (e.g. sanitation engineer) first recorded 1939.
underarm: 1816, "underhand" (in ref. to a style of throwing), from under + arm. First attested 1908 in dressmaking sense of "seams on the lower half of the arm-hole;" as a euphemism for armpit, it is attested from 1930s, popularized by advertisers.
indiscreet: "imprudent, not discrete" (early 15c.) and indiscrete "not containing distinct parts" (c.1600) are both from L. indiscretus "unseparated;" the former via an O.Fr. or M.L. secondary sense. Indiscretion as a euphemism for "immoral act" is from c.1600.
hothouse: 1451, "bath house," from hot + house. In 17c. a euphemism for "brothel" (cf. massage parlor); the meaning "glass-roofed structure for raising plants" is from 1749.
tarnation: 1784, Amer.Eng. alteration of darnation (itself a euphemism for damnation), influenced by tarnal (1790), from phrase by the Eternal (God).
challenge: 1292, from O.Fr. chalenge "accusation, claim, dispute," from L. calumnia "trickery" (see calumny). Accusatory connotations died out 17c. Meaning "a calling to fight" is from 1530. Challenged as a euphemism for "disabled" dates from 1985.
miss (n.): "the term of honour to a young girl" [Johnson], shortened form of mistress. Earliest use (1645) is for "prostitute, concubine;" sense of "title for a young unmarried woman, girl" first recorded 1666. In the 1811 reprint of the slang dictionary, Miss Laycock is given as an underworld euphemism for "the monosyllable."
screw (v.): "to twist (something) like a screw," 1599, from screw (n.). Slang meaning "to copulate" dates from at least 1725, on the notion of driving a screw into something. Meaning "a prostitute" also is attested from 1725. Slang meaning "an act of copulation" (n.) is recorded from 1929. First recorded 1949 in exclamations as a euphemism.
defective: late 15c., from Fr. défectif (14c.), from L. defectivus, from defect-, pp. stem of deficere (see deficient). A euphemism for "mentally ill" from 1898 to c.1935.
criminy: also crimine, 1680s; it looks like It. crimine "crime" but likely is simply another euphemism for Christ as a swear-word.
confinement: 1590s, from Fr. confinement (16c.), from confiner (see confine). As a euphemism for "childbed" it dates from 1774 (the M.E. expression was Our Lady's bands).
expect: 1393 (implied in expectant), from L. expectare "await, hope," from ex- "thoroughly" + spectare "to look," freq. of specere "to look at" (see scope (1)). Fig. sense of "anticipate, look forward to" developed in Latin. Used since 1817 as a euphemism for "be pregnant."
blaze (1): "fire," O.E. blæse "a torch, flame," from P.Gmc. *blason, from PIE *bhles- "shine," from base *bhel- (see black). The verb is early 13c. Blazes as a euphemism for "hell" dates from 1818.
pre-owned: 1964, Amer.Eng., from pre- + pt. of own (v.). An automobile dealer's euphemism for used.
defense: c.1300, from O.Fr. defens, from L. defensum "thing protected or forbidden," from neut. pp. of defendere "ward off, protect" (see defend). First used 1935 as a euphemism for "national military resources." Defense mechanism in psychology is from 1913.
ruddy: O.E. rudig, probably from rudu "redness," related to read "red" (see red). As a British slang euphemism for bloody (q.v.), first recorded 1914.
darn (2): tame curse word, 1781, Amer.Eng. euphemism for damn, said to have originated in New England when swearing was a punishable offense; if so, its spread was probably infl. by 'tarnal, short for Eternal, as in By the Eternal (God), favorite exclamation of Andrew Jackson, among others. Related: Darndest (superl., 1844).
sacre bleu: stereotypical Fr. oath, 1869, from Fr. sacré bleu, lit. "holy blue," a euphemism for sacré Dieu (1768), "holy God."
belie: O.E. beleogan "to deceive by lies," from be- + lie (v.1) "to lie, tell lies." Current sense of "to contradict as a lie" is first recorded 1640s. The other verb lie once also had a formation like this, from O.E. belicgan, which meant "to encompass, beleaguer," and in M.E. was a euphemism for "to have sex with" (i.e. "to lie with carnally").
mortuary: early 14c., from Anglo-Fr. mortuarie "gift to a parish priest from a deceased parishioner," from M.L. mortuarium, from neut. of mortuarius "pertaining to the dead," from L. mortuus, pp. of mori "to die" (see mortal). Meaning "place where bodies are kept temporarily" first recorded 1865, a euphemism for earlier deadhouse.
lavatory: late 14c., "washbasin," from L. lavatorium "place for washing," noun use of neut. of adj. lavatorius "pertaining to washing," from lavatus, pp. of lavare "to wash" (see lave). Sense of "washroom" is first attested 1650s; as a euphemism for "toilet, W.C.," it is attested from 1924.
facetious: 1592, from Fr. facétieux, from facétie "a joke," from L. facetia, from facetus "witty, elegant," of unknown origin, perhaps related to facis "torch." It implies a desire to be amusing, often intrusive or ill-timed. "Facetiæ in booksellers' catalogues, is, like curious, a euphemism for erotica." [Fowler]
meddle: late 13c., "to mingle," from O.N.Fr. medler (O.Fr. mesler) "to mix, mingle, to meddle," from V.L. *misculare, from L. miscere "to mix" (see mix). Meaning "to concern oneself" (usually disparaging) is attested from early 15c. From mid-14c. to 1700, it also was a euphemism for "have sexual intercourse."
expectorate: c.1600, "to clear out the chest or lungs," from L. expectoratus, pp. of expectore "scorn, expel from the mind," lit. "make a clean breast," from ex- "out" + pectus (gen. pectoris) "breast." Use as a euphemism for "spit" is first recorded 1827. Original sense in expectorant (1811).
plain (adj.): c.1300, "flat, smooth," from O.Fr. plain, from L. planus "flat, even, level" (see plane (1)). Sense of "evident" is from, c.1300; meaning "simple, sincere, ordinary" is recorded from late 14c. In reference to the dress and speech of Quakers, it is recorded from 1827; of Amish and Mennonites, from 1904. Of appearance, as a euphemism for "ill-favored, ugly" it dates from 1749.
cloaca: 1656, Mod.L., euphemism for "sewer," from L. cloaca "sewer," from cluere "to cleanse," from PIE base *klu- "to rinse, clean."
indecent: 1563, "unbecoming, in bad taste," from L. indecentem, from in- "not" + decentem (see decent). Sense of "offending against propriety" is from 1613. Indecent assault (1861) originally covered sexual assaults other than rape or intended rape, but by 1934 it was being used as a euphemism for "rape."
dysphemia: 1884, "substitution of a vulgar or derogatory word or expression for a dignified or normal one," from Gk. dys- "bad, abnormal, difficult" (see dys-) + pheme "speaking," from phanai "speak" (see fame). The opposite of euphemism. Rediscovered 1933 from Fr. formation dysphémisme (1927).