From the second edition (1989):
zigzag, n., a., adv.
(ˈzɪgzæg) Also as two words or with hyphen; also 8 zic-zac, zigzac(k, ziczag. [ad. F. zigzag (1680 in Hatz.-Darm.); ultimate origin unknown; partly symbolic, the two different vowels suggesting the two different directions. Cf. G. zickzack (Sperander, 1727), said to be first used of fortifications (sense 3a).]

A. n.

1. a. A series of short lines inclined at angles in alternate directions; a line or course having sharp turns of this kind; concr. something characterized by such lines or turns. Orig. in phr. in zigzag (= F. en zigzag).

1712 J. James tr. Le Blond's Gardening 42 Steps of Grass laid in Zic-Zac [Note, The French call this an Allée en Zic-Zac, for its Likeness to a Machine so called]. Ibid. 215 Chevrons, or Checks of Grass in Zig-Zac. 1728 Chambers Cycl. s.v. Alley, An Alley in Ziczac, is that which has too great a Descent. 1822 J. Parkinson Outl. Oryctol. 139 The larger tubercles placed in zig-zag. 1892 E. Reeves Homeward Bound 299 Entering by the beautiful Gate of Justice, and winding in zigzag through the thickness of the tower.
1766 Colman & Garrick Cland. Marr. ii. ii, Here's none of your strait lines here—but all taste—zig-zag—crinkum crankum—in and out. 1830 M. Donovan Dom. Econ. I. 235 Twisted into a serpent, or bent into a zig-zag. 1856 Merivale Rom. Emp. xl. IV. 495 The other [road] was practicable for carriages, and for this purpose was made to climb the acclivity with a zigzag. 1871 Nesbitt Catal. Slade Coll. Glass 6 Terminating with a turquoise zig-zag. 1880 Meredith Tragic Com. xi, Dashing his finger in a fiery zig-zag along the line for her pen to follow. 1884 Ruskin Pleas. Eng. iii. §87. (1885) 121 The hieroglyphic use of the zigzag, for water, by the Egyptians.

b. Each of such lines or turns: chiefly in pl.

1728 Pope Dunc. i. 124 Nonsense precipitate, like running Lead, That slipp'd thro' Cracks and Zig-zags of the Head. 1775 Twiss Trav. Port. & Sp. 64 A winding road, which forms thirteen zig-zags. 1833 L. Ritchie Wand. Loire 182 A cap, laced and ribanded in all manner of zig-zags. a1861 Clough Poems, Ite Domum Saturae 11 The lightning zigzags shoot across the sky. 1865 G. Macdonald Alec Forbes lxxiv, The button made many a zigzag from side to side of the table. 1875 Bennett & Dyer Sachs' Bot. 742 The grand curve of growth‥does not assume the form of a continuous curve, but shows a number of small zigzags.

c. fig.

1781 Cowper Conversation 861 Though such continual zig~zags in a book, Such drunken reelings, have an awkward look. 1796 Burke Regic. Peace ii. Wks. 1842 II. 311 The fanaticks going straight forward and openly, the politicians by the surer mode of zigzag. 1815 Jane Austen Emma xv, The little zigzags of embarrassment. 1913 Roosevelt Autobiogr. 579 Our policy is apt to go in zigzags, because different sections of our people exercise at different times unequal pressure on our government.

2. A road or path turning sharply at angles in alternate directions, esp. so as to reduce the gradient on a steep slope; each of the sharp turns forming such a road.

1728 Swift My Lady's Lam. 184 How proudly he talks Of zigzags and walks. 1848 Thackeray Bk. Snobs vi, I thread the doubtful zig-zags of Mayfair. 1855 Alford in Life (1873) 250 Up the valley of the Adour to Arreau, a village approached by zigzags. 1890 ‘R. Boldrewood’ Col. Reformer xiii, Many years before the Zig Zag [sc. railway in New South Wales] was chopped out of the sidelings.

3. Applied spec. to other things of a zigzag shape. a. Fortif. A trench leading towards a besieged place, constructed in a zigzag direction so as not to be enfiladed by the defenders; a boyau. b. Archit. A chevron-moulding. c. Fisheries. (See quot.)

a. 1733 Budgell Bee IV. 67 A Battery began in the Morning to play upon the Cavalier of the Bastion Ghiera; the Night following the Zic-zacs were continued. 1834–47 J. S. Macaulay Field Fortif. (1851) 239 The zig-zags may often require a greater relief than the parallels.
b. 1814 Scott Border Antiq. I. 59 The dancette, as the figure is termed in heraldry, or zig-zag. 1826 W. A. Miles Deverel Barrow 4 The chevron or zig zag, that favorite British ornament so prominent in Egyptian remains. 1884 Ruskin Pleas. Eng. iii. §87. (1885) 119 The Norman zigzag.
c. 1875 Knight Dict. Mech., Zigzag, a winding chute on the face of a dam to enable fish to ascend.

4. Collectors' name for a shell, or a moth, with zigzag marking.

1815 S. Brookes Conchol. 157 Zigzag, Cypræa Ziczac.

5. (Zig(-)Zag.) A proprietary name for cigarette paper.

1909 Official Gaz. (U.S. Patent Office) 14 Dec. 594/1 Braunstein & Cie, Paris.‥ Zig Zag.‥ Cigarette-paper. 1927 Trade Marks Jrnl. 13 Apr. 675 Zig-zag No. 114.‥ Cigarette papers. Société anonyme des anciens Établissements Braustein Frères‥, Paris. 1968 Current Slang (Univ. S. Dakota) Fall 52 Zig-zag, paper of high quality which is commonly used in rolling marijuana. 1977 C. McFadden Serial (1978) xxx. 67/1 She stuffed her‥Zig Zags back into her purse.

6. attrib., as zigzag machine, a sewing machine with a swing needle that may be used to produce a zigzag stitch and decorative stitches derived from it.

[1950 Vogue Pattern Book Apr.–May 81/2 It was Pfaff that developed the famous Zig-Zag Model 130.] 1952 Consumers' Res. Bull. Sept. 11/1 All the zig-zag machines but one‥were heavy. 1963 Which? June 165/2 For plain zig zag machines, the width of the stitch limits the range of patterns they can make. 1978 Detroit Free Press 5 Mar. d14 (Advt.), Fashionmate zig zag machine featuring our front drop-in bobbin.

B. adj.

1. a. Having the form of a zigzag; turning sharply at angles in alternate directions; characterized by turns of this kind.

1750 Dobbs in Phil. Trans. XLVI. 543 Striking it with a wriggling Motion from Side to Side, in a zigzag Way. 1767 Hamilton ibid. LVIII. 11 Flashes of forked, or zig-zag lightning. 1784 Cowper Task ii. 364 He‥transforms old print To zig-zag manuscript. 1792 Wordsw. Descrip. Sketches 236 Up from the lake a zigzag path will creep. 1835 Dickens Sk. Boz, River, Away jogs the boat in a zig~zag direction. 1860 Tyndall Glac. i. ii. 11 A kind of zigzag channel had been worn on the side of the mountain.
fig. 1798 Mathias Purs. Lit. (ed. 7) 327 Be regular: from A to B proceed; I hate your zig-zag verse, and wanton heed. 1861 J. Pycroft Ways & Words 192 The old joke of the zigzag jury who said ‘Guilty’ and ‘Not guilty’ alternately, all through the assizes. 1863 Cowden Clarke Shaks. Char. vi. 145 All the brood of zig-zag politicians. 1897 Goschen in Hansard's Parl. Deb. XLVII. 597 Our policy is to have as little of the zigzag policy‥as possible.

b. Archit. Applied to a moulding or other ornament of a zigzag pattern: cf. A. 3b.

c1765 Gray Let. to Bentham Wks. 1825 II. 286 The chevron-work (or zig-zag moulding). 1815 J. Smith Panorama Sci. & Art I. 136 Channels in various forms, some plain zigzag, some like network, and some spiral. 1840 C. Wordsw. Greece 58 Columns of green basalt, with fantastic zigzag ornaments.

c. Bot. Applied to the stem of a plant, or to a plant having such a stem.

1796 Martyn Lang. Bot. (ed. 2), Zigzag, used by some English writers for Flexuose. 1796 Withering Brit. Plants (ed. 3) III. 579 Zigzag Ladies smock. 1819 Rees Cycl., Zigzag Trefoil,‥a term sometimes applied by farmers to the perennial red clover, marl grass, or wild red clover.

2. Having zigzag markings. (Chiefly Nat. Hist.)

1785 Latham Gen. Syn. Birds V. 61 Zigzag Bittern. 1796 Nemnich Polygl.-Lex. 946 Zigzag chama, Venus castrensis.

3. Mil. slang (chiefly U.S.). Drunk.

1918 Hamilton & Corbin Echoes from over There (1919) 125 He got a trifle zig-zag. 1919 W. H. Downing Digger Dialects 54 Zig-zag, drunk. 1923 E. Paul Impromtu 149 He groped and floundered‥not completely ‘zigzag’. 1930 Brophy & Partridge Songs & Slang Brit. Soldier 181 Zig-zag, drunk. 1961 Times 27 Apr. 17/2 What is that to a nation which uses some 400 synonyms for ‘drunk’—from ‘all geezed up’ to ‘zig-zag’?

4. Comb., as zigzag-shaped adj.; zigzag fashion, zigzag-wise quasi-advbs.; zigzag connection Electr. Engin., a form of star connection of three-phase circuits, each branch of which is interconnected and contains portions of two consecutive phases.

1758 Goldsm. Mem. Protestant (1895) II. 149 A Way very commodious cut, Zigzag Fashion. 1846 F. Brittan tr. Malgaigne's Man. Oper. Surg. 236 The interline is zigzag shaped. 1877 Huxley & Martin Elem. Biol. 26 Its joints are bent zig-zag-wise. 1922 P. Kemp Alternating Current Electr. Engin. (ed. 2) xiii. 188 This affects the magnetising current and may result in an appreciable increase in iron loss owing to flux distortion, and to minimize this effect zig-zag connections are sometimes adopted. 1947 R. Lee Electronic Transformers & Circuits iii. 47 Unbalanced direct current in the half-wave rectifiers requires larger transformers than in the full-wave rectifiers. This is partly overcome in three-phase transformers by the use of zigzag connections.

C. adv. In a zigzag manner or direction.

c1730 Burt Lett. N. Scot. (1754) II. 132 It is almost incredible‥how nimbly they skip,‥turning Zic Zac to such Places as are passable. 1764 Veicht in Phil. Trans. LIV. 287 The lightening is observed to run not in strait line, but zig zag. 1846 Greener Sci. Gunnery 244 When he ignites a rocket, it may go straight forward, or zig-zag. 1862 Beveridge Hist. India III. viii. iv. 374 The road‥led zig~zag up the side of a precipitous mountain.