From the second edition (1989):
‖coup, n.3
(kuː) [F. coup (ku) blow, stroke:—OF. colp, cop = Pr. colp, cop, It. colpo:—late L. colpus (Salic Law), colapus (Law of the Alemanns) blow, stroke, for L. colaphus blow with the fist, cuff, a. Gr. κόλαϕος cuff, buffet. Adopted in ME. in a literal sense, and naturalized in pronunciation (see coup n.1); re-introduced in the 18th c. in fig. sense, as a non-naturalized word, with modern Fr. pronunciation (exc. that in Eng. the vowel is made long); it also occurs in many French phrases and expressions borrowed in English.]

1. A blow, a stroke (that one sustains). rare.

1793 F. Burney Lett. 4 Oct., This is a terrible coup, so soon after your union.

2. a. A stroke, a move (that one makes); a successful move, a ‘hit’. †at one coup (= Fr. tout d'un coup): at one stroke, at once.

1791 Gentl. Mag. LXI. ii. 829 A corrupt majority, who have at one coup overthrown all that is good. 1845 Disraeli Sybil (1863) 280 Alfred is the only fellow who has made a coup. 1849 Thackeray Pendennis xl, Henry Foker is engaged to his cousin‥not a bad coup of Lady Rosherville's that. 1883 D. C. Murray Hearts III. 77 He hailed the chance for a grand theatrical coup.

b. = coup d'état.

1852 North Brit. Rev. XVI. 584 A tyranny‥which it required the ‥coup of the 9th Thermidor to overthrow. 1958 Economist 26 July 267 The coup in which Nuri es-Said‥and the Hashemite dynasty were destroyed.

3. Billiards. The act of holing a ball without its first striking another ball, which occasions a forfeit.

1770 J. Love Cricket 5 Or when the Ball, close cushion'd, slides askew, And to the op'ning Pocket runs, a Cou. 1873 Bennett & Cavendish Billiards 5 A miss lost one and a coup three.

4. Among North American Indians: A successful stroke; esp. one that captures the weapon or horse of an enemy. Also attrib., as coup-stick (see quot. 1876).

1841 G. Catlin N. Amer. Indians I. 27 Each one‥recited his exploits, and his ‘coups’ or deaths. 1876 R. I. Dodge Plains G. West (Farmer Americanisms), Giving the Coup‥the term indicates that it was‥named by the old French trappers, predecessors of the Hudson Bay Company. When a foe has been struck down in a fight, the scalp belongs to him who shall first strike the body with knife or tomahawk. This is the coup. 1876 J. G. Bourke Jrnl. 15 June (D.A.), Making ‘coup’ sticks, which are long willow branches, about 12 feet from end to end, stripped of leaves and bark and having each some distinctive mark in the way of feathers, bells, [etc.]…in dividing the spoil, each man claims the animals first struck by his ‘coup’ stick. 1921 Glasgow Herald 12 Nov. 7 Chief Plenty Coos laid his coupstick (symbol of tribal authority) and his war bonnet on the tomb. 1963 Beaver Summer 33/2 Befeathered coup stick (to touch an enemy or count coup was a braver act than killing him).

5. French phrases frequent in English use. a. coup d'état (ku deta) [F. état state]: a sudden and decisive stroke of state policy; spec. a sudden and great change in the government carried out violently or illegally by the ruling power.

1646 Howell Lewis XIII, Life of Richelieu 157 These were the two first Coups d'estat, stroaks of State that he made. 1811 Wellington in Gurw. Desp. VIII. 352, I shall be sorry to commence the era of peace by a coup d'état such as that which I had in contemplation. 1859 Gen. P. Thompson Audi Alt. II. xcviii. 87 A coup d'état as effectual for the time as that of Louis Napoleon [2 Dec. 1851].

b. coup de force (ku də fɔrs) [lit. stroke of force]: a sudden, violent action.

1835 J. S. Mill in Lond. Rev. II. 277 Their tampering with that measure was a coup de force. 1949 I. Deutscher Stalin xiii. 535 The only chance of breaking out of their impasse lay in a coup de force.

c. coup de foudre (ku də fudr) [lit. stroke of lightning]: a sudden unforeseen occurrence; a revelation; also, love at first sight.

1779 Mrs. E. Boscawen Let. 23 June in C. Aspinall-Oglander Admiral's Widow (1942) xvii. 96 This sentence‥was a perfect coup de foudre bursting amidst our tranquil scenes. 1936 ‘R. Hyde’ Check to your King xiv. 163 Rumours of similar French coups de foudre were everywhere. 1955 Times 28 July 10/6 There is the first sight of it, virgin and gleaming from the makers, and the coup de foudre that makes us instantly one with it.

d. coup de glotte (ku də glɔt) [F. glotte glottis]: the glottal stop.

1909 in Webster. 1922 G. B. Shaw Let. 27 Jan. (1960) 16 Afterall and Westminsterabbey may have to be unlearned for the stage, as the coup de glotte before a vowel, German fashion, is often necessary for emphasis, audibility in a big house. 1962 John o' London's 19 July 65/3 The much-abused, but little understood, coup de glotte.

e. coup de grâce (ku də gras) [lit. stroke of grace]: a blow by which one condemned or mortally wounded is ‘put out of his misery’ or dispatched quickly; hence fig. a finishing stroke, one that settles or puts an end to something.

1699 Garth Dispens. iv. 43 Whilst Poor Pretenders trifle o're a Case, You but appear, and give the Coup de Grace. 1745 P. Thomas Jrnl. Anson's Voy. 326 Not being indulged, like other Malefactors, with the Coup de Grace, the favourable Blow, to put an End to their Pain. 1820 Blackw. Mag. VI. 481/1 Whenever the baker's stomach fails him, he meets his coup de grace in the adulterated drugs of his friend the apothecary.

f. coup de main (ku də mɛ̃) [lit. stroke of hand]: ‘a sudden and vigorous attack, for the purpose of instantaneously capturing a position’ (Stocqueler Mil. Encycl.); also transf.

1758 Misc. in Ann. Reg. 373/2 Coup de main, and Manœuvre, might be excusable in Marshal Saxe. 1779 J. Moore View Soc. Fr. II. liv. 46 Laudohn retook it‥by the most brilliant coup-de-main that perhaps ever was struck. 1801 Wellington in Gurw. Desp. I. 365 This place can be taken by a coup de main, and probably in no other manner. 1877 Clery Min. Tact. xiii. 178 To secure the guns from the coup de main on the left.

g. coup d'œil (ku dœj) [F. œil eye]: (a) A glance taking in a general view; concr. a view or scene as it strikes the eye at a glance.

1739 Gray Let. to West 21 Nov., This is the first coup d'œil, and is almost all I am yet able to give you an account of. 1785 European Mag. VIII. 468 The spot is a beautiful coup d'œil, a woody recess. 1837 Major Richardson Brit. Legion i. (ed. 2) 2 We embraced one of the most magnificent coup-d'œils it is possible to conceive. 1890 Eng. Illustr. Mag. No. 87. 227 The first magnificent coup d'œil.

(b) Mil. The action or faculty of rapidly taking a general view of a position and estimating its advantages and disadvantages.

1839 Sir C. Napier in W. N. Bruce Life iv. (1885) 127 This is my first coup d'œil, and may be a very erroneous one. 1853 in Stocqueler Mil. Encycl. 1864 H. Ainsworth J. Law i. iv. (1881) 91 He was but a mediocre general, lacking the coup d'œil of genius.

h. coup de poing (ku də pwɛ̃) [lit. stroke of fist]: a Chellean implement in the form of a shaped flint; a hand-axe; also attrib.

1912 R. Munro Palæolithic Man ii. 30 The Saint Acheul deposits, which have yielded an enormous quantity of flint implements of the coup-de-poing type. 1923 A. L. Kroeber Anthropol. xiv. 398 The coup-de-poing being a comparatively effective, regularly shaped, symmetrical implement involving both an ideal of form and a tolerable, rough skill to produce. 1932 Antiquity VI. 190 These flake industries seem to be quite distinct from the coup-de-poing industries.

i. coup de soleil (ku də sɔlɛj) [F. soleil sun]: a sunstroke. Obs.

1772 Duchess of Northumberland Diary 23 Apr. (1926) 166 The use is to prevent the wearer from receiving a Coup de Soleil. 1794 Sullivan View Nat. I. 260 Even a coup de soleil is to be counteracted by the external application of‥volatile alkali. 1814 Q. Rev. Oct. 202 Many European soldiers [in India] were struck dead by a coup de soleil. 1834 Medwin Angler in Wales I. 4, I‥got the malaria at Rome, a coup-de-soleil at Naples. 1867 S. W. Baker Nile Tributaries xxii. 553 Bacheet had a slight coup de soleil.

j. coup de théâtre (ku də teɑtr): a theatrical hit; a sensational turn or action in a play; transf. any sudden sensational act.

1747 H. Walpole Lett. to Mann June 26, This coup de theâtre procured Knight his Irish coronet. 1889 Morley Walpole xi. 225 The House of Commons is the worst place in the world for coups de théatre.

k. coup de vent (ku də vɑ̃) [F. vent wind]: a whirlwind; a gale.

1831 Disraeli Yng. Duke I. i. xi. 93 Oh, what a coup-de-vent! 1853 C. Brontë Villette I. xiii. 237 Monsieur went off like a coup de vent the other night.

l. In other phrases, now rare or obs. in Eng. use, as coup d'éclat, a stroke which makes a sensation; coup d'essai, a first attempt; coup de maître, an action worthy of a master, a master-stroke.

1668 Dryden Dram. Poesie 54 Any Character or humour wherein he would show a Coup de Maistre, or his highest skill. 1676 G. Etherege Man of Mode iv. ii, Sir Fop. I have been endeavouring at a song!‥ 'Tis my Coup d' Essay in English. 1712 Steele Spectator No. 324 ⁋1 To put the Watch to a total Rout, and mortify some of those inoffensive Militia, is reckon'd a Coup d'éclat. 1760 Foote Minor i. (1798) 20 Ay, that will be a coup de maitre. 1768 —— Devil on 2 Sticks iii. (1794) 57 It may do for a coup d'essai, and prove no bad foundation for a future engagement. 1819 T. E. Bowdich Mission to Ashantee i. vi. 123 It would be a coup d'éclat much more important and agreeable, if he could settle the Warsaw palaver as well. 1845 J. W. Croker in Q. Rev. Sept. 526 This work seems‥to be a respectable coup d'essai, written with some thought. 1893 Conan Doyle Mem. Sherlock Holmes 270 There are limits‥to our friend's intelligence. It would have been a coup-de-maître had he deduced what I would deduce and acted accordingly.