Green’s Dictionary of Slang

nig n.³

gin.

1859, 1860		Hotten Dict. of Modern Sl. etc.
1864, 1867, 1870		Hotten Sl. Dict.
1873		Sl. Dict.
1882		Sydney Sl. Dict. (2 edn) 11: Nig - Gin.
1923		Eve. Teleg. (Angus, Scot.) 11 July 11/4: For example, top for pot, yennep for penny, nig for gin, and nodol for London.