Green’s Dictionary of Slang

1. to die.

1848		G.F. Ruxton Life in the Far West (1849) 3: Them three’s all ‘gone under’.
1850		‘Ned Buntline’ G’hals of N.Y. 16: Little Jule and Gussy, who aint half so strong an’ able as Mary, Suse, or me, must slowly pine away an’ go under.
1875		J.H. Warren Crying Shame of NY 245: Under any other possibilities than those which exist to day in our large cities for self-help, these frisky waifs would ‘go under’ in a twinkling.
1885		Bulletin (Sydney) 22 Aug. 6/3: A born humourist was [...] lost to the world when Mr. Thomas Galvin, the genial, light-hearted ‘finisher’ of the noted Kilmainham (Dublin) Gaol, went under, full of years, ‘rheumatiz,’ and honours.
1886		‘Ned Buntline’ Buffalo Bill 50: ‘’tend to the colonel, for he is pretty nigh gone under’.
1892		H. Nisbet Bushranger’s Sweetheart 299: That’s Jack Casey gone under. I thought often that he wouldn’t last long.
1905		‘Central Connecticut Word-List’ in DN III:i 10: go under, v. Perish.
1908		Magnet 13 June 16: Frank Dennis had not gone under without making a fight of it.
1911		C.E. Mulford Bar-20 Days 26: We’ll fight to the finish. You’ll be the first to go under if you gets any smart.
1922		Joyce Ulysses 104: He has seen a fair share go under in his time, lying around him field after field.
1936		L. Pound ‘American Euphemisms for Dying’ in AS XI:3 199: Gone under.
1948		(con. 1944) N. Mailer Naked and Dead 231: He buys an ordinary seaman’s card [...] from a drunk who is about to go under.

2. to go bankrupt.

1860		D. Rice Orig. Effusions 77: My impression is that he will go under [DA].
1872		Schele De Vere Americanisms 303: A man who has thus gone under, as commercial slang has it, and finds himself unable, for want of capital, to begin a new ‘business.’.
1879		J. Payn ‘Finding His Level’ in High Spirits I 234: Poor John Weybridge Esq. became as friendless as penniless, and eventually ‘went under,’ and was heard of no more.
1888		R. Barnett Police Sergeant C 21 31: You must have met, during the course of your experience [...] with men who have gone under.
1890		Pall Mall Gazette 29 May 5/1: He asks us further to state that the strike is completely at an end, the society having gone under [F&H].
1893		A. Bierce letter 18 Apr. in Pope Letters of Ambrose Bierce (1922) 32: I have just lost another publisher — by failure. Schulte, of Chicago [...] has ‘gone under’.
1900		Bulletin (Sydney) 17 Feb. 13/2: When Matthias went under years ago there was a general impression that he had a vast sum of money planted somewhere, and meant to lead a life of revelry thereon when his troubles were over.
1912		Bulletin (Sydney) 14 Nov. 15/1: It is because he is unable to purchase the necessary implements of his craft that the mortgage-burdened cocky so often goes under.
1935		(con. 1920s) J.T. Farrell Judgement Day in Studs Lonigan (1936) 561: Where would a guy’s dough be safe? [...] If he socked it in a bank, the bank might go under.
1967		(con. 1940s) M. Dibner Admiral (1968) 215: Slack off, Rollo. At the rate you’re winning friends here, this hotel’ll go under.
1975		E. Torres Carlito’s Way 25: It was a jive raid but it blew the liquor license and the old P went under.
1997		(con. 1960s) A. Frewin London Blues 101: Still, I can’t ever imagine our heavy and light industries going under.
2000		M. Collins Keepers of Truth 5: Sam’s scared shitless we’re going under.

3. in fig. use, to fail or decrease in some way.

1879		J. Payn ‘An Aunt by Marriage’ in High Spirits I 310: We were ‘going under,’ as the gradual sinking in the social scale is significantly termed.
1902		Bulletin (Sydney) 22 Nov. 25/4: If hubby likes the siren sort, then the wife should be a better siren than the other cat, and that outside animal would go under.
1903		Bulletin (Sydney) 17 Dec. 26/2: Wakeful was beaten, and all our other ‘certs.’ went under.
1966		J. Holledge Great Aust. Gamble 78: Allen’s horse went under by a head to a fast finishing rival.

4. (Aus. Und.) to be imprisoned.

1968		J. Alard He who Shoots Last 22: If you blast this informer you’ll go under.
1982		G. Newbold Big Huey 37: I knew that if I went under on the heroin charge I was in for a big one.
1984		B. Ellem Doing Time 190: go under: refers to the possibility of being caught or found guilty [ibid.] 199: went under: the past tense of ‘go under’. He ‘went under’ for five years refers to a five-year sentence.
1990		Tupper & Wortley Aus. Prison Sl. Gloss. 🌐 Go under. To be found guilty.