From the second edition (1989):
(ˈkʊkɪ) Also cooky, cookey. [prob. a. Du. koekje (ˈkuːkjə) dim. of koek cake: this is app. certain for U.S.; but for Scotland historical evidence has not been found.]

1. a. In Scotland the usual name for a baker's plain bun; in U.S. usually a small flat sweet cake (a biscuit in U.K.), but locally a name for small cakes of various form with or without sweetening. Also S. Afr. and Canad.

c1730 Burt Lett. N. Scot. (1760) II. xxiv. 272 In the Low-Country the Cakes are called Cookies. 1808 W. Irving Salmag. (1824) 368 Those notable cakes, hight new-year cookies. 1816 Scott Antiq. xv, Muckle obliged to ye for your cookies, Mrs. Shortcake. 1852 D. G. Mitchell Dream Life 97 Very dry cookies, spiced with caraway seeds. 1852 Barter Dorp & Veld 107 Cookies, or unleavened cakes of coarse meal, baked on the grid-iron. 1870 B. Harte Luck Roar. Camp 227 (Farmer) He lost every hoof and hide, I'll bet a cookey! 1897 E. Glanville Tales from Veld 51 Raking the ‘cookie’ from the fire-place, whence it came baking hot. 1935 M. de la Roche Young Renny xxiv. 214 Mary was arranging plates of bread and butter, thick ginger cookies,‥and a bowl of halved peaches. 1968 Globe & Mail (Toronto) 17 Feb. 6/2 Children sneaking cookies from a cookie jar.

b. Comb., as cookie-pusher (U.S. colloq.), a counter attendant; fig., a man leading a futile social life; spec., a diplomat allegedly devoting more attention to protocol or social engagements than to his work; cookie-shine (humorous), a tea-party (cf. tea-fight).

1942 Berrey & Van den Bark Amer. Thes. Slang §449/1 Cookie pusher‥a party attender. Ibid. §452/3 Dandy, ‘dude’ ‥cookie pusher. Ibid. §825/15 Ladies' man‥cookie-pusher. 1946 Word Study May 2/1 State Department officials have long been called ‘cookie pushers’. 1961 Times 30 May 10/6 The chairman of the House sub-committee‥still‥dismisses all diplomatists as ‘cooky-pushers’. 1962 Economist 29 Sept. 1211/3 The popular image of the cookie-pusher in Foggy Bottom. 1863 Reade Hard Cash v, Conversaziones, cookey-shines, etcetera. 1867 N. & Q. Ser. iii. XII. 195/2 From the frequent appearance of these [cookies] at tea-parties, the latter are irreverently spoken of as Cookie Shines.

2. slang (orig. U.S.). a. A woman; esp. an attractive girl. b. A man, often with defining word.

1920 Collier's 6 Mar. 42/3 That girl friend of yours is a cookie—hey, what? 1928 Chicago Tribune 7 Oct. (Comics) 2 What a swell bunch of cookies you turned out to be. 1942 Amer. Mercury Oct. 436/1 Just about the toughest cookie ever born. 1948 F. Brown Murder can be Fun (1951) x. 146 A smart cookie, that Wilkins. 1953 W. R. Burnett Vanity Row xvi. 110 He's a real tough cookie and you know it. 1959 R. Longrigg Wrong Number ii. 27, I met a cookie I know.‥ She said you'd said Faustus was like Oklahoma.

3. A bomb. Air Force slang.

1943 in Amer. Speech (1944) XIX. 310/1, I am flying in one of three Lancasters which will drop hundreds of incendiaries as well as 4,000-pound ‘cookies’. 1944 R. Dimbleby in War Report (B.B.C.) (1946) xiv. 280 But I did see heavy bombs, cookies, going down into the brown smoke.

4. Colloq. phr. (chiefly U.S.): (that's) how (or the way) the cookie crumbles, (that is) how the position resolves itself; that is the way it is.

1957 Sat. Even. Post 7 Sept. 59 From then on, that's the way the cooky crumbled. I enjoyed having good ratings, but I didn't enjoy the viciousness of the railbirds' thrusts at Berle. 1959 Wenzell Brown Cry Kill iv. 45 No matter how the cookie crumbled, Mamma Ida was in for a bad time. 1961 Wodehouse Ice in Bedroom v. 40 Oh well, that's the way the cookie crumbles. You can't win 'em all. 1964 Listener 16 Apr. 612/2 We shall not know how, as the Americans say, the cookie crumbles.