Green’s Dictionary of Slang

1. (also othersider) a Western Australian [note tother side n.].

1859		Age (Melbourne) 24 June 4/4: [T]he very jealousy breathed throughout the letters stamps them as emanating from a disappointed, and a not over-sighted ‘’tother-sider’.
1882		Sth Aus. Register (Adelaide) 16 Dec. 6/2: Only one fellow saw any sarcasm in the remark, and he, I suspect, was ‘a tothersider.’ West Australians have an insuperable objection to undue haste .
1890		H. Lawson ‘Who’s Dot Pulleteen?’ in Roderick (1967–9) I 78: ‘Let dose mountains fall and hide us’ / Gry benighded odersiders.
1898		W.A. Sun. Times (Perth) 9 Jan. 1/1: Typhoid has already began to make itself felt - as usual among the t’othersiders.
1902		W.A. Sun. Times (Perth) 9 Mar. 1/1: The National Produce Show was an eye-opener to many t’othersiders.
1910		Bulletin (Sydney) 18 Aug. Red Page/3: Westralia, the youngest of the States, has not produced any bards yet. Some three or four books of verse printed there were written by t’other-siders.
1999		G. Seal Lingo 30: eastern staters, a modern continuation of the traditional t’othersiders that developed during the Western Australia gold rushes of the 1890s, though the term had earlier currency.

2. a transported felon.

1860		Bendigo Advertiser (Vic.) 26 June 3/1: [S]ome others may find themselves before his worship treated with [...] his ‘thorough knowledge of them as ’tothersiders.
1867		Queenslander (Brisbane) 15 June n.p.: Sometimes an old ‘t’other sider’ will tell the assembled crowd how he got lagged.
1871		Wkly Times (Mlebourne) 6 May 2/3: ‘I knows the t’other-siders well’.
1880		Bulletin (Sydney) 20 Mar. 4/4: In one corner a couple of foot-pads, euphuistically called ‘’t’othersiders,’ are planning a raid upon some escort.
1885		Bulletin (Sydney) 29 Aug. 22/1: Mac. looked at the prisoner with peculiar vindictiveness – mistook him for a ‘T’other-sider.’.

3. attrib. use of sense 2.

1900		Bulletin (Sydney) 28 Apr. 13/3: Born in Westralia, reared and educated in it, Phillips declined to believe there was a superior spot on earth, or better Government in creation. [...] Thriving under such conditions, he was taken by surprise when the goldfields broke out. The ‘Tothersider’ invasion was too much for him.
1905		H. Lawson ‘Joseph’s Dreams and Reuben’s Brethren’ in Roderick (1967–9) II 98: Some T’othersider prospectors / Had been there poking round.

4. an Australian from the eastern part of the country [note tother side n.].

1900		Bulletin (Sydney) 20 Oct. 14/2: [T]he only Groper present suddenly broke out: ‘Well, look ’ere chaps, the t’othersiders come over ’ere, and if they make a bit ’o splosh, off they goes back to their own blanky country – and good luck to ’em, say I.’.
1900–10		Stephens & O’Brien Materials for a Dict. of Aus. Sl. [unpub. ms.] 161: ’TOTHERSIDERS: Westralian nickname for people coming from New South Wales and Victoria to Westralia.
1993		Aus. Word Map 🌐 othersider a person living on the other side of the Nullarbor Plain. Also, t’othersider.