Online Etymology Dictionary

discotheque (n.): 1954 as a French word in English; nativized by 1965, from French discothèque "nightclub with recorded music for dancing," also "record library," borrowed 1932 from Italian discoteca "record collection, record library," coined 1927 from disco "phonograph record" + -teca "collection," probably on model of biblioteca "library."
discount (n.): 1620s, "abatement," alteration of 16c. French descompte, from Medieval Latin discomputus (source of Italian disconto), from discomputare (see discount (v.)). Meaning "deduction for early payment" is from 1680s; meaning "reduction in the price of goods" attested by 1837.
discount (v.): 1620s, "reckon as an abatement or deduction," from Old French desconter (13c., Modern French décompter), from Medieval Latin discomputare, from dis- (see dis-) + computare "to count" (see count (v.)). Hence, "to abate, deduct" (1650s), and figurative sense "to leave out of account, disregard" (1702). Related: Discounted; discounting.
discountenance (v.): "put to shame," 1570s, from Middle French descontenancer (16c.) "to abash," from des- (see dis-) + contenancer (see countenance).
discourage (v.): mid-15c., discoragen, from Middle French descourager, from Old French descoragier, from des- "away" (see dis-) + corage (see courage). Related: Discouraged; discouragement; discouraging.
discourse (n.): late 14c., "process of understanding, reasoning, thought," from French discours, from Latin discursus "a running about," in Late Latin "conversation," from past participle stem of discurrere "run about," from dis- "apart" (see dis-) + currere "to run" (see current (adj.)). Sense of "formal speech or writing" is first recorded 1580s.
discourse (v.): 1540s, from discourse (n.). Related: Discoursed; discoursing.
discourteous (adj.): 1560s; see dis- + courteous. Related: Discourteously.
discourtesy (n.): 1550s; see dis- "opposite of" + courtesy.
discover (v.): c. 1300, "divulge, reveal, disclose," from Old French descovrir "uncover, unroof, unveil, reveal, betray," from Late Latin discooperire, from Latin dis- "opposite of" (see dis-) + cooperire "to cover up" (see cover). At first with a sense of betrayal or malicious exposure (discoverer originally meant "informant"); the meaning "to obtain knowledge or sight of what was not known" is from 1550s. Related: Discovered; discovering.
discovery (n.): 1550s, "fact of discovering;" see discover + -y (1). Earlier in this sense was discovering (mid-14c.). Meaning "that which is discovered" is from 1630s.
discredit (v.): 1550s, from dis- "opposite of" + credit (v.). Related: Discredited; discrediting; discreditable; discreditably.
discreet (adj.): mid-14c., "morally discerning, prudent, circumspect," from Old French discret "discreet, sensible, intelligent, wise," from Latin discretus "separated, distinct," in Medieval Latin "discerning, careful," past participle of discernere "distinguish" (see discern). Meaning "separate, distinct" in English is late 14c.

Spellings discrete and nativized discreet co-existed until after c. 1600, when discreet became the common word for "careful, prudent," and discrete was maintained in philosophy, medicine, music and other disciplines that remembered Latin and made effort to obey it. Related: Discreetly.
discrepancy (n.): mid-15c. (discrepance), from Latin discrepantia "discordance, discrepancy," from discrepantem (nominative discrepans), present participle of discrepare "sound differently, differ," from dis- "apart, off" (see dis-) + crepare "to rattle, crack" (see raven). Related: Discrepancies.
discrete (adj.): "separate, distinct," late 14c., from Old French discret, discre, and directly from Latin discretus "separated;" see discreet. Related: Discretely.
discretion (n.): c. 1300, dyscrecyun, "moral discernment," from Old French discrecion or directly from Late Latin discretionem (nominative discretio) "discernment, power to make distinctions," in classical Latin "separation, distinction," noun of state from past participle stem of discernere "to separate, distinguish" (see discern). Phrase at (one's) discretion attested from 1570s, from sense of "power to decide or judge" (late 14c.); the age of discretion (late 14c.) in English law was 14.
discretionary (adj.): 1680s (implied in discretionarily); see discretion + -ary.
discriminate (v.): 1620s, from Latin discriminatus, past participle of discriminare "to divide, separate," from discrimen (genitive discriminis) "interval, distinction, difference," derived noun from discernere (see discern). The adverse (usually racial) sense is first recorded 1866, American English. Positive sense remains in discriminating. Related: Discriminated. Also used 17c. and after as an adjective meaning "distinct."
discriminating (adj.): "possessing discernment," 1792, present participle adjective from discriminate (v.).
discrimination (n.): 1640s, "the making of distinctions," from Late Latin discriminationem (nominative discriminatio), noun of action from past participle stem of discriminare (see discriminate). Especially in a prejudicial way, based on race, 1866, American English. Meaning "discernment" is from 1814.
It especially annoys me when racists are accused of 'discrimination.' The ability to discriminate is a precious facility; by judging all members of one 'race' to be the same, the racist precisely shows himself incapable of discrimination. [Christopher Hitchens]
discriminatory (adj.): 1828; see discriminate + -ory.
discursive (adj.): 1590s, from Middle French discursif, from Medieval Latin discursivus, from Latin discursus "a running about" (see discourse). Related: Discursively.
discus (n.): 1650s, from Latin discus "discus, disk," from Greek diskos "disk, quoit, platter" (see disk (n.)).
discuss (v.): mid-14c., "to examine, investigate," from Latin discuss-, past participle stem of discutere "to dash to pieces, agitate," in Late Latin and Vulgar Latin also "to discuss, investigate" (see discussion). Meaning "examine by argument, debate" is from mid-15c. Related: Discussed; discussing.
discussion (n.): mid-14c., "examination, investigation, judicial trial," from Old French discussion "discussion, examination, investigation, legal trial," from Late Latin discussionem (nominative discussio) "examination, discussion," in classical Latin, "a shaking," from discussus, past participle of discutere "strike asunder, break up," from dis- "apart" (see dis-) + quatere "to shake" (see quash). Meaning "a talking over, debating" in English first recorded mid-15c. Sense evolution in Latin appears to have been from "smash apart" to "scatter, disperse," then in post-classical times (via the mental process involved) to "investigate, examine," then to "debate."
disdain (v.): late 14c., from Old French desdeignier "disdain, scorn, refuse, repudiate," from des- "do the opposite of" (see dis-) + deignier "treat as worthy" (see deign). Related: Disdained; disdaining.
disdain (n.): mid-14c., desdegne "scorn, contempt," earlier dedeyne "offended dignity" (c. 1300), from Old French desdeigne, from desdeignier (see disdain (v.)). Sometimes in early Modern English shortened to sdain, sdainful. Related: disdainful; disdainfully.
disease (n.): early 14c., "discomfort, inconvenience," from Old French desaise "lack, want; discomfort, distress; trouble, misfortune; disease, sickness," from des- "without, away" (see dis-) + aise "ease" (see ease). Sense of "sickness, illness" in English first recorded late 14c.; the word still sometimes was used in its literal sense early 17c.
diseased (adj.): late 15c., past participle adjective from Middle English verb disesen "to make uneasy; inflict pain" (mid-14c.), later "to have an illness or infection" (late 14c.); "to infect with a disease" (late 15c.), from disease (n.).
disembark (v.): 1580s, from Middle French desembarquer, from des- (see dis-) + embarquer (see embark). Related: Disembarkation; disembarked; disembarking.
disembodied (adj.): 1742, past participle adjective from disembody (1714), from dis- "not" + embody. Related: Disembodiment.
disembowel (v.): c. 1600, from dis- + embowel. Earlier form was disbowel (mid-15c.); embowel, with the same meaning, is attested from 1520s. Related: Disemboweled; disembowelment.
disempower (v.): 1813; see dis- + empower. Related: Disempowered; disempowerment.
disenchant (v.): 1580s, from Middle French desenchanter (13c.), from des- (see dis-) + enchanter "to enchant" (see enchant). Related: Disenchanted; disenchanting; disenchantment. Carlyle coined disenchantress (1831).
disenfranchise (v.): "deprive of civil or electoral privileges," 1640s, from dis- + enfranchise. Earlier form was disfranchise (mid-15c.). Related: Disenfranchised; disenfranchisement.
disengage (v.): c. 1600 in figurative sense; 1660s in literal sense of "detach," from dis- "do the opposite of" + engage (q.v.). Related: Disengaged; disengaging.
disengagement (n.): 1640s; see disengage + -ment.
disentangle (v.): 1590s; see dis- + entangle. Related: Disentangled; disentangling.
disfavor (n.): 1530s; see dis- "the opposite of" + favor (n.). As a verb, from 1560s. Related: Disfavored; disfavoring.
disfavour: chiefly British English spelling of disfavor (q.v.); for ending, see -or. Related: Disfavoured; disfavouring.
disfigure (v.): late 14c., from Old French desfigurer "disfigure, alter, disguise, destroy," from Medieval Latin diffigurare, from Latin dis- (see dis-) + figura "figure," from figurare "to figure" (see figure (n.)). Related: Disfigured; disfiguring.
disfigurement (n.): 1630s, from disfigure + -ment.
disfunction (n.): 1927, variant of dysfunction (q.v.).
disfunctional (adj.): 1951, variant of dysfunctional.
disgorge (v.): late 15c., from Old French desgorgier "to disgorge, pour out," from des- (see dis-) + gorge "throat" (see gorge). Related: Disgorged; disgorging; disgorgement.
disgrace (v.): 1550s, "disfigure," from Middle French disgracier (16c.), from Italian disgraziare, from disgrazia "misfortune, deformity," from dis- "opposite of" (see dis-) + grazia "grace" (see grace). Meaning "bring shame upon" is from 1590s. Related: Disgraced; disgracing. The noun is 1580s, from Middle French disgrace (16c.).
disgraceful (adj.): 1590s, "graceless," opposite of graceful; see dis- + graceful. Meaning "full of disgrace" (1590s) is from disgrace + -ful. Related: Disgracefully.
disgruntle (v.): 1680s, from dis- "entirely, very" + obsolete gruntle "to grumble" (Middle English gruntelen, early 15c.), frequentative of grunt (v.).
disgruntled (adj.): past participle adjective from disgruntle.
disguise (v.): c. 1300, from Old French desguiser (11c.) "disguise, change one's appearance," from des- "away, off" (see dis-) + guise "style, appearance" (see guise). Originally primarily "to put out of one's usual manner" (of dress, etc.). Oldest sense preserved in phrase disguised with liquor (1560s).
It is most absurdly said, in popular language, of any man, that he is disguised in liquor; for, on the contrary, most men are disguised by sobriety. [Thomas De Quincey, "Confessions of an English Opium-Eater," 1856]
Related: Disguised; disguising.