Green’s Dictionary of Slang

1. an elderly woman.

1849		Sam Sly 10 Mar. 3/2: The two dangerous tabs, Mother LI—d [...] alias the Twin Gossips, not to let their tongues run so fast about their neighbours.
1890		Bulletin (Sydney) 2 Aug. 14/1: It happened that a kid-gloved predecessor had been soaping down the tabs with ‘A great work being done’ and similar tommy-rot, but the new man wrote that it was all humbug – half a dozen common women lectured by a dozen stiff-’uns.
1909		J. Ware Passing Eng. of the Victorian Era 239/1: Tabs (Theatrical). Ageing women. Abbreviation of Tabby, one of the common names for the cat, always associated with ancient women.
1934		‘Dryblower’ in Sun. Times Perth) 9 Dec. 9/8: You’ll rarely find roguery, bunkum or blab / In a forty-year widowed and well tuckered tab / Who’s asking for dresses discarded.

2. (Aus.) a young woman.

1913		Sport (Adelaide) 25 Jan. 11/2: They Say [...] That Leo McC. is seriously thinking about leaving the Unley tabs, and taking on Barbara F.
1918		Aussie (France) IX Dec. 4/1: The Froggy tabs are very susceptible to the charms of music.
1924		Gippsland Times (Vic.) 15 Sept. 1/4: He‘s learned to curse and swear / And chucked glad eyes to other tabs when the wifie wasn’t there.