Online Etymology Dictionary

debase: 1568, from base "low," on analogy of abase.
debate: c.1300, from Fr. debattre (13c.), orig. "to fight," from de- "down, completely" + batre "to beat."
debauch: 1595, from M.Fr. debaucher "entice from work or duty," from O.Fr. desbaucher "to lead astray," supposedly lit. "to trim (wood) to make a beam" (from bauch "beam," from Frank. balk). A sense of "shaving" something away, perhaps, but the root is also said to be a word meaning "workshop," which gets toward the notion of "to lure someone off the job;" either way the sense evolution is unclear.
"Debauchee, n. One who has so earnestly pursued pleasure that he has had the misfortune to overtake it." [Ambrose Bierce, "Devil's Dictionary," 1911]
debenture: c.1455, from L. debentur "there are due," said to have been the first word in formal certificates of indebtedness.
debility: 1474, from M.Fr. debilite, from L. debilitatem (nom. debilitas), from debilis "weak," from de- "from, away" + -bilis "strength," from PIE base *bel- (see Bolshevik).
debit: c.1450, from M.Fr. debet, from L. debilitum "thing owed," neut. pp. of debere "to owe" (see debt).
debonair: c.1225, from O.Fr., from de bon' aire "of good race," originally used of hawks, hence, "thoroughbred" (opposite of Fr. demalaire). Used in M.E. to mean "docile, courteous," it became obsolete and was revived with an altered sense of "pleasant, affable" (1685).
Deborah: prophetess and judge in the O.T., in Heb., lit. "bee" (thus the name is the same as Melissa).
deboshed: 1599, Anglicized spelling of Fr. pronunciation of debauched "dissolute" (see debauch). Obsolete in England after mid-17c., retained in Scotland, and given a revival of sorts by Scott (1826), so that it turns up in 19c. literary works.
debrief: "obtain information (from someone) at the end of a mission," 1945, from de- + brief (v.).
debris: 1708, from Fr. debriser "break down, crush," from O.Fr. briser "to break," from L.L. brisare, possibly of Gaulish origin.
debt: c.1290, from O.Fr. dete, from L. debitam "thing owed," neut. pp. of debere "to owe," originally, "keep something away from someone," from de- "away" + habere "to have" (see habit). Restored spelling after c.1400 from M.E. dette. The KJV has detter three times, debter three times, debtor twice and debtour once.
debunk: 1923, first used by U.S. novelist William Woodward (1874-1950), the notion being "to take the bunk out of things" (see bunk).
debut (n.): 1751, fig. sense from Fr. débuter "make the first stroke at billiards," also "to lead off at bowls" (a game akin to bowling), from but "mark, goal," from O.Fr. bot "end." The verb is first attested 1830. Debutante is 1801, from fem. prp. of Fr. débuter; slang shortening deb dates from 1920.
decade: c.1451, "ten parts" (of anything; originally in ref. to the books of Livy), from M.Fr. decade, from L.L. decadem (nom. decas), from Gk. dekas (acc. dekada) "group of ten." Meaning "ten years" is 1594 in Eng.
decadence: 1549, from M.Fr. decadence (1413), from M.L. decadentia "decay," from decadentem (nom. decadens) "decaying," prp. of decadere "to decay," from L. de- "apart, down" + cadere "to fall" (see case (1)). Used of periods in art since 1852, on Fr. model. Decadent is from 1837.
decal: 1937 shortening of decalcomania, from Fr. decalcomanie, from decalquer, "transferring of a tracing from specially prepared paper to glass, porcelain, etc." (in vogue in France 1840s, England 1862-64), from de- "off" + calquer "to press," from It. calcare, from L. calcare "to tread on, press."
Decalogue: 1382, from M.Fr. decalogue, from L. decalogus, from Gk., from the phrase hoi deka logoi used to translate "Ten Commandments" in Septuagint.
Decameron: 1609, from Boccaccio's 14c. collection of 100 tales supposedly told over 10 days, from Gk. deka "ten" + hemera "day."
decant: 1633, "pour off the clear liquid from a solution by gently tipping the vessel," originally an alchemical term, from Fr. decanter, from M.L. decanthare, from canthus "corner, lip of a jug," from Gk. kanthos "corner of the eye," on a perceived resemblance between the beaked lip of a jug and the corner of the eye. Decanter is 1712.
decapitate: 1611, from Fr. decapiter, from L.L. decapitatus pp. of decapitare, from L. de- "off" + caput (gen. capitis) "head" (see head).
decathlon: 1912, from deca "ten" + Gk. athlon "contest, prize." A modern Olympic event consisting of 10 challenges.
decay: c.1460, from O.Fr. decair, from V.L. *decadere "to fall off," from L. cadere "to fall" (see case (1)). Meaning "gradual decrease in radioactivity" is from 1897.
decease: c.1330, from Fr. deces, from L. decessus "death," lit. "departure" (euphemism for mors), from pp. stem of decedere "die," from de- "away" + cedere "go" (see cede). Still used with a tinge of euphemism.
deceit: c.1300, from O.Fr. deceite, fem. pp. of deceveir (see deceive).
deceive: c.1300, from O.Fr. deceveir, from L. decipere "to ensnare, take in," from de- "from" or pejorative + capere "to take" (see capable).
deceleration: 1897, coined from de- "do the opposite of" + (ac)celeration.
December: c.1000, from O.Fr. decembre, from L. December, from decem "ten;" tenth month of the old Roman calendar, which began with March. The -ber in four L. month names is probably from -bris, an adjectival suffix. Tucker thinks that the first five months were named for their positions in the agricultural cycle, and "after the gathering in of the crops, the months were merely numbered."
If the word contains an element related to mensis, we must assume a *decemo-membris (from *-mensris). October must then be by analogy from a false division Sep-tem-ber &c.; Perhaps, however, from *de-cem(o)-mr-is, i.e. "forming the tenth part or division," from *mer- ..., while October = *octuo-mr-is. [T.G. Tucker, "Etymological Dictionary of Latin"]
decent: 1539, "proper to one's station or rank," also "tasteful," from M.Fr. decent, from L. decentem (nom. decens, gen. decentis), prp. of decere "to be fitting or suitable," from PIE *deke-, from base *dek- "to take, accept, to receive, greet, be suitable" (cf. Gk. dokein "to appear, seem, think," dekhesthai "to accept;" Skt. dacasyati "shows honor, is gracious," dacati "makes offerings, bestows"). Meaning "kind, pleasant" is from 1902. Decency is 1567 in sense of "appropriateness," 1639 in sense of "modesty." Are you decent? (1949) was originally backstage theater jargon for "are you dressed."
deception: c.1412, from pp. stem of L. decipere (see deceive).
decibel: 1928, coined from L. decibus "tenth," from decem "ten" + bel unit for measuring sound, after Alexander Graham Bell.
decide: c.1380, from O.Fr. decider, from L. decidere "to decide," lit. "to cut off," from de- "off" + cædere "to cut" (see cement). Sense is of resolving difficulties "at a stroke." Originally "to settle a dispute;" meaning "to make up one's mind" is attested from 1830. Decided in the adj. sense of "resolute" is from 1790. Decisive is 1611. A decided victory is one whose reality is not in doubt; a decisive one goes far toward settling some issue.
deciduous: 1688, from L. deciduus "that which falls off," from decidere "to fall off," from de- "down" + cadere "to fall" (see case (1)). Originally with reference to leaves, petals, teeth, etc.; specific sense of "trees whose leaves fall off" (opposed to evergreen) is from 1778.
decimal: 1608, from M.L. decimalis "of tithes or tenths," from L. decimus "tenth," from decem "ten." Applied to Arabic notation before modern sense of "decimal fractions" emerged.
decimation: 1549, from L.L. decimationem, from L. decimare "the removal or destruction of one-tenth," from decem "ten." Killing one in ten, chosen by lots, from a rebellious city or a mutinous army was a common punishment in classical times. Earliest sense in Eng. was of a tithe; decimate has been used (incorrectly, to the irritation of pedants) since 1663 for "destroy a large portion of."
decipher: 1528, from de- + cipher.
decision: c.1454, from M.Fr. decision, from L. decisionem (nom. decisio), see decide.
decisive: 1611, see decide.
deck (n.): 1466, probably aphetic of M.L.G. verdeck, a nautical word, from ver- "fore" + decken "to cover, put under roof," from P.Gmc. *thackjam (related to thatch), from PIE *(s)tog-/*(s)teg- "cover" (see stegosaurus). Sense extended early in Eng. from "covering" to "platform of a ship." "Pack of cards" is 1593, perhaps because they were stacked like decks of a ship. The verb sense of "knock down" is first recorded c.1953, probably from notion of laying someone out on the deck. Deck chair (1884) so called because they were used on ocean liners. Tape deck (1949) is in ref. to the flat surface of old reel-to-reel tape recorders.
deck (v.): "adorn" (as in deck the halls), c.1500, from M.Du. dekken "to cover," from the same P.Gmc. root as deck (n.). Replaced O.E. þeccan.
declaim: c.1385, from L. declamare, from de- intens. prefix + clamare "to cry, shout" (see claim). At first in Eng. spelled declame, but altered under infl. of claim.
declare: c.1325, from L. declarare "make clear," from de- intensive prefix + clarare "clarify," from clarus "clear."
declasse: 1887, from Fr. déclassé, pp. of déclasser "to cause to lose class."
declassify: 1865, originally a term in logic; with reference to state secrets, 1946; from de- + classify.
decline: c.1327, "to turn aside, deviate," from O.Fr. decliner "to bend, turn aside," from L. declinare "to bend from, inflect," from de- "from" + clinare "to bend," from PIE *klei-n-, suffixed form of *klei "to lean" (see lean (v.)). Sense has been altered since 15c. by interpretation of de- as "downward." Meaning "not to consent" is from 1631. Astronomical declination (c.1386) and grammatical declension (1565) are both ult. from L. noun derivative declinatio.
declivity: 1612, from L. declivitatem (nom. declivitas), from declivis "a sloping downward," from de- "down" + clivus "a slope," from PIE *klei-wo-, suffixed form of *klei "to lean" (see lean (v.)).
decoction: 1398, from pp. stem of L. decoquere "to boil down," from de- + coquere "to cook" (see cook (n.)). Decoct is attested from c.1420.
decolletage: 1894, from décolleté "low-necked" (1831), from Fr. décolleter "to bare the neck and shoulders," from des- "from" + collet, dim. of col (L. collum) "neck" (see collar).
decolonization: 1938, from de- + colonization.
decommission: 1922, originally with reference to warships, from de- + commission (v.).