Green’s Dictionary of Slang

frost; thus zneesy/zneezy adj., frosty (of weather).

1725		New Canting Dict. n.p.: znees Frost, or Frozen; Zneesy Weather; Frosty Weather [...] znus the same as znees.
c.1750–1882		B.M. Carew Life and Adventures.
1785, 1788, 1796		Grose Classical Dict. of the Vulgar Tongue.
1809		G. Andrewes Dict. Sl. and Cant n.p.: znees frost or snow [...] zneezy weather frosty weather.
1811		Lex. Balatronicum.
c.1850		Duncombe New and Improved Flash Dict.
1859		Matsell Vocabulum 97: znees Ice; snow; frost.
1881		Trumble Sl. Dict. (1890).