Green’s Dictionary of Slang

the number nine.

1859, 1860		Hotten Dict. of Modern Sl. etc.
1864, 1867, 1870		Hotten Sl. Dict.
1873		Sl. Dict.
1882		Sydney Sl. Dict. (2 edn) 11: Enin Yanneps - Ninepence.
2001		J. Burkardt ‘Back Sl.’ Wordplay 🌐 eenin: nine.