Green’s Dictionary of Slang

1. (Aus., also stiffen out) to die.

1885		Bulletin (Sydney) 15 Aug. 14/3: He has reminiscences of No. so-and-so, who had ‘stiffened out’ as he called it.
1885		Bulletin (Sydney) 29 Aug. 5/3: The white men had an incorporated junk of yellow agony suspended by the neck from a she-oak, and were seated around on stumps betting drinks on how many kicks the son of Confucius would give before stiffening.

2. (Aus.) in fig. use, to punish.

1890

Bulletin (Sydney) 12 July 7/4: A Sydney girl, aged fifteen, charged with stealing money, umbrellas, bags, &c., from little girls on their way to school, accounted for the possession of some money and property by saying it was given her by another girl to go ‘stiff’ in a race for a gold medal at a skating rink. She was further ‘stiffened’ by a sentence of seven days’ imprisonment and three years in Shaftsbury Reformatory.

3. to kill, to murder; lit. or fig.

1890		‘Rolf Boldrewood’ Colonial Reformer II 56: ‘Stiffen those blank dingoes!’ roared Gregor.
1902		Bulletin (Sydney) 19 Jul. 26/3: Among the remarks which the writer heard from the sex that boasts a gentle spirit and a murdered fowl in its hat were, ‘Lay them out!’ ‘Stiffen the brute!’ ‘Sling him, Ruddy; sling him!’.
1911		L. Stone Jonah 54: Serve the cow right [...] ’Ope it stiffens ’im! [Ibid.] 104: ‘Gawd, ’e’s stiffened ’im!’ ‘I ’eard ’is neck crack!’.
1933		Townsville Daily Bull. (Qld) 3 June 12/4: I started to rip the floorin’ up in that hut so that I could stiffen that snake.
1948		J. O’Connor Come Day – Go Day (1984) 110: ‘Don’t answer me back, or I’ll stiffen you,’ Kitty shouted. ‘You good-for-nothing looking craythur!’.
1968		S. Gore Holy Smoke 12: I stiffen the bear with one flamin’ punch.

4. (Aus., also stiffen out) to knock someone unconscious, thus stiffener, that which knocks one out (lit. or fig.).

1885		Bulletin (Sydney) 31 Jan. 6/3: [The yacht] was prominently brought under the notice of the British public [...] resultant upon her pugnacious commander having, on one fine morning, ‘flattened out,’ and ‘stiffened,’ and ‘shifted the ears,’ of a number of the crew and certain other people who had behaved in what Juba was pleased to consider an objectionable manner.
1895		Truth (Sydney) 10 Mar. 5/5: Dibbs got a regular stiffener over his resolution.
1900		Bulletin (Sydney) 13 Oct. 14/2: ‘That’s all blanky fine, [...] but look at my load! why didn’t you take a spreader and lay her out?’ ‘For God’s sake, don’t talk like that,’ said the husband, excited for the first time, ‘or she’ll stiffen the whole blanky lot of us!’.
1908		Ohin-e-muri Gaz. (NZ) 27 Jan. 3/1: This person has on several occasions stated that he will willingly do three years in gaol to stiffen me out.
1911		L. Stone Jonah 127: They said yous ’ud stiffen me if I cum in.
1938		R.L. Bellem ‘Grappling Trilby’ in Popular Sports June 🌐 So I’m to stiffen your tramp again, am I?
1949		R. Park Poor Man’s Orange 272: The right bloke had better get her, or I’ll stiffen him out, as God’s my judge.
1972		E. Grogan Ringolevio 47: Solly [...] stiffened him with the sanded-down sock.
1991		M.B. ‘Chopper’ Read Chopper From The Inside 50: [It] slowed him down enough for the ex-champ to stiffen him with a very nice right uppercut.

5. (Aus.) in fig. use, to ruin, to undermine, to ‘put paid to’; to interfere with a racehorse’s performance; thus n. stiffener, one who pursues such activties.

1895		Truth (Sydney) 3 Mar. 1/3: Favourites are ‘stiffened,’ ‘welchers’ won’t pay their debts, jockeys cheat their masters.
1895		Truth (Sydney) 2 June 3/4: Sometimes the witnesses are ‘stiffened’ before the come before the Commission.
1897		Truth (Sydney) 10 Jan. 3/7: But smart stiffener as he was, he never succeeded in inducing Old Ben [...] to put one in his ‘kick’.
1900		Bulletin (Sydney) 8 Sept. 28/1: The English ’tecs, however, are going to ‘stiffen’ that game by simply taking their prisoner back ‘west-about,’ via Australia.
1904		Sun. Times (Perth) 4 Sept. 4/7: So I tell the old Joe Rail / [...] / And I bluff ’em off and scale / When I’ve tipped a stiffened ’orse.
1906		Morwell Advertiser (Vic.) 21 Dec. 2s/1: McCarthy, O’Connor, / And Jockey McDonagh, Arranged with the ‘bookies’ to ‘stiffen’ the nag.