Green’s Dictionary of Slang

a lazy, fat woman; thus fat fussock, a fat, strapping woman; old fussock, an ill-kempt old woman.

c.1698		B.E. Dict. Canting Crew n.p.: Fussocks, a meer Fussocks, a Lazy, Fat-Ars’d Wench. A Fat Fussocks, a Fulsom, Fat, Straping Woman.
1725		New Canting Dict. [as cit. c.1698].
1737, 1759, 1760, 1776		Bailey Universal Etym. Eng. Dict. [as cit. c.1698].
1785, 1788, 1796		Grose Classical Dict. of the Vulgar Tongue n.p.: Fussock, a lazy fat woman. An old fussock; a frowsy old woman.
1811		Lex. Balatronicum.
1812		Spirit of Irish Wit 56: An Irish officer happened to fine at the fashionable table of a city fussock, who had waddled her way [...] to a splendid house in Berkeley-square.
1823		Egan Grose’s Classical Dict. of the Vulgar Tongue.
1859		Matsell Vocabulum 35: fussock An old fat woman.
1881		Trumble Sl. Dict. (1890).
1995		K. Atkinson Behind the Scenes at the Museum 122: ’What are you looking at?’ Rachel snapped eventually and Ada smiled that false smile she had, [...] and said, ’Nowt,’ and when Rachel persisted said spitefully ’Nobbut a big, fail fuzzock,’ and Rachel knew enough of their stupid broad dialect by now to know that she was an ugly donkey.