Green’s Dictionary of Slang

1. a convict.

1865		H. Kingsley Hillyars and Burtons (1870) 63: There is no euphemism invented yet for the word ‘convict’ [...] [some] might fancy that ‘Old hand,’ ‘Vandemonian,’ or even ‘Sydney Sider’ were not particularly offensive.
1890–1904		Farmer & Henley Sl. and Its Analogues.

2. a native of New South Wales; thus Sydneyside adj.

[1864		J. Armour Diggings, the Bush, and Melbourne 18: One was related as a piece of confidence from an absent comrade, the circumstance happening on ‘the Sydney side’].
1865		H. Kingsley Hillyars and Burtons (1870) 360: The Sydney-Sider’s loss is considered by him to have been far greater.
1869		Australiasian (Melbourne) 17 July 8/5: The derivation of Sydney-sider and Derwenter, &c is obvious.
1899		Age (Melbourne) 8 July 4/4: Sydneysiders will find mention of the pluck and resourcefulness of many old identities.
1900		Bulletin (Sydney) 6 Jan. 11/2: Sydney-siders at B[roken].H[ill]. are mostly policemen. [...] The ‘unspeakable local Council’ asked for a bill authorising it to light up; it was the Sydneyside Parliament that bashi-bazouked the measure.
1911		E.S. Sorenson Tent Life in Life in the Aus. Backblocks 103: Scores of Sydneysiders every year spend their summer vacation in tents, forming little communities in quiet spots where there is fishing and perhaps shooting.
1918		Aussie (France) 4 Apr. 1/1: Neither are we strong, silent, lean-jawed, six-footers. We are smallish Sydneysiders – all windbags.
1924		N.Z. Truth 24 Aug. 8/2: The Sydney-siders [...] should not have muc difficulty winning all their matches.
1931		Times Literary Supplement 1 Oct. 738/1: A fear of its [i.e. Melbourne’s] writers [...] echoed the nationalist emotion, but in abstract terms that lacked the appeal of the Sydney-siders.
1940		Edmonton Jrnl (Alberta) 20 Feb. 4/3: The famous Sydney harbor bridge [...] cost £10,000,000 and Sydneysiders say it was worth every penny.
1955		Sydney Morn. Herald 14 May 9/3: ‘I am a Sydneysider by birth’.
1967		Age (Melbourne) 3 May 17/5: Mr Kattler’s heart was stung so painfully by the barbs of Sydneysiders.
1970		(con. 1941) R. Beilby No Medals for Aphrodite 161: Don’t you Sydneysiders know what a Sandgroper is? We haven’t got any Harbour Bridges over there.
1980		N. Marsh Photo-Finish 199: He was a self-made man, a Sydneysider who had pulled himself up by his own boot-strings.
1994		Sydney Morn. Herald 8 Oct. 79/3: In 1985 17 per cent of Sydneysiders approved of married people sleeping with someone other than their spouses.
2004		Australian 8 Oct. 🌐 High property prices are pushing Sydneysiders towards South Australia and Victoria.
2017		T. Spicer Good Girl Stripped Bare 57: We [i.e. Queenslanders] think Sydneysiders are tossers.