Green’s Dictionary of Slang

1. (also mid) a midshipman.

1785		C. Dibdin [song title] ‘The Middy’s Parting’.
1812		Southey letter 30 Dec. Letters (1856) II 315: I have written to Bedford to learn what mids of the Victory fell in that action.
1818		‘A. Burton’ Adventures of Johnny Newcome I 34: The Mids, as oft as John drew near To stare about him, seemed to sneer, For John [...] They knew was but a ‘Johnny Raw’.
1829		Life on Board a Man-of-War 88: ‘He is coming, sir,’ said the middy, ‘but we will need to carry him up’.
1831		Navy at Home I 34: Mr. Lackwit, the son and heir of a rich tradesman in town — ‘mate of a watch,’ and a passed mid.
1827		‘An Officer of the Line’ Military Sketch-book I June c.207: The giving of the word [of command] from the ‘middy’.
1832		Quid 11: Three saplings, youths; the two first, middies.
1833		Launceston Advertiser (Tas.) 3 Jan. 420/1: [T]he giving of the word from the Middy, always accompanied by a d—.
1833		Ely’s Hawk & Buzzard (NY) Sept. 21 n.p.: Snd one of your Birds [...] to find out how the Middy’s get along [...] Now, Commodore, just do a midshipman the honor to pass a few remarks .
1842		Flash (N.Y.) 10 July 3/1: Her passions thus excited, she rushed madly onward in her career of vice, and at one time she was the common gamester of all the Middies in our Navy Yard.
1843		Bellew Memoirs of a Griffin I 139: ‘Go it, my middies!’.
1846		Censor (London) 18 Jan. 3/1: A fellow named Etheridge, a middy in the East India service [...] was charged with a most brutal assault.
1849		Leeds intelligencer 18 Aug. 3/4: ‘All in vain,’ muttered the mid [...] launch her ahead, bowman’.
1850		(con. 1843) Melville White-Jacket (1990) 5: In the steerage, the middies were busy raising loans to liquidate the demands of their laundress.
1864		Appleton Crescent (WI) 13 Aug. 1/3: ‘Try, try again,’ sang that devil of a middy, Jerry Boom.
1867		J. Greenwood Unsentimental Journeys 139: I’ve got an uncle a soldier [...] and a nephew a middy in Green’s service.
1878		Besant & Rice By Celia’s Arbour III 41: We went [...] into the gallery, where there were a dozen middies and young naval fellows.
1882		Nat. Police Gaz. (NY) 30 Sept. 2/2: [T]he dainty middies and dandy lieutenant commanders who have been doing the polo drill and ball room flirtation service.
1888		Soldiers’ Stories and Sailors’ Yarns 6: They were capital specimens of the genus ‘middy’.
1891		Sporting Times 24 Jan. 2/2: ‘Modesty becomes thee, and a mid is always modest’.
1894		G.A. Sala Things I Have Seen I 104: The witty author of that comedy had [...] been rated as a middy on board the guard-ship.
1904		Marvel 22 Oct. 16: A rollicking young middy, off to join his ship.
1915		G. Malone Gallipoli diary in Phillips, Boyack & Malone Great Adventure (1988) 19 May 51: There were about seven Naval Officers, ‘middies’ or ‘snotties’ as they are endearingly called by Captains and Lieutenants.
1920		Bulletin (Sydney) 12 Feb. 14/2: A tall, good-looking middy .
1925		N. Lucas Autobiog. of a Thief 42: She described me as: ‘The most wonderful little middy!’.
1932		Sheboygan (WI) Press 17 Sept. 8/3: Like students the world over, the middies have developed among themselves a ‘patois’ of slang that, although highly descriptive when understood, forces an outsider to seek an interpreter.

2. (Aus., also midi) a measure of beer, approx. 285ml (10fl oz), or the glass that holds it [the measure is ‘middle sized’; however, note Hornadge, Aus. Slanguage (1986): ‘In New South Wales a middy of beer is a small glass (10oz) while in Western Australia it shrinks [...] down to a 7 oz measure’].

1941		Sydney Morn. Herald 13 Feb. 3/8: This glass called a ‘middy’ will hold 10cc of beer — exactly half a pint.
1951		Cusack & James Come in Spinner (1960) 331: A hand reached out, passed over a ten-shilling note, and took a middy from her.
1957		‘Nino Culotta’ They’re a Weird Mob (1958) 25: Those big glasses are called schooners and those small ones are called middies.
1969		A. Buzo Rooted I iii: Ever had a middy of Bacardi neat?
1977		K. Gilbert Living Black 130: Angus and his brother Doug went in for a couple of middies.
1981		A. Weller Day of the Dog 80: [They] play pool and drink a few slow middies to while away the time.
1996		Penguin Bk of More Aus. Jokes 176: Take them all now with a midi of beer.
1998		P. Doyle (con. late 1950s) Amaze Your Friends (2019) 70: I poure a middy of black Johnny Walker.
1999		G. Seal Lingo 30: In New South Wales there are [...] middy, a 10 fluid ounce glass (though the same order will only get you 8 fluid ounces in Perth).
2007		D. McDonald Luck in the Greater West (2008) 1: He wished he was able to be drunk at three in the arvo but he couldn’t risk a middy.
2016		D. Whish-Wilson Old Scores [ebook] Over a few middies Heenan talked of utilising Swann’s counterintelligence skills to keep the premier’s offices ‘clean’.