Green’s Dictionary of Slang

1. cheap, inferior gin.

1820		‘Peter Corcoran’ ‘King Tims the First’ in Fancy 28: The ruin you’ve drawn down upon your lips, / Has made it rather foggy.
1827		P. Cunningham New South Wales II 278: She [...] had a thimble of ruin on credit of her prize in ten minutes.
1839		W.A. Miles Poverty, Mendicity and Crime; Report 168: Cocum gonnofs flash by night the cooters in the boozing kens, and send their lushy shicksters out to bring the ruin in.
1841		‘The Scavenger’s Ball’ Dublin Comic Songster 10: They made such a clatter, drank ruin and gatter.
1857		‘Ducange Anglicus’ Vulgar Tongue.
1861		(con. 1840s–50s) H. Mayhew London Labour and London Poor II 375/1: I haven’t no father and don’t remember one, and mother might do well but for the ruin (gin).
1882		Sydney Sl. Dict. 9/2: Shake this mob, Bill, and speel to the den, and let our lushy shicksters bring the ruin in. Get away from these fellows, Bill, and come away home, and let our tippling women bring in the gin.

2. (UK juv.) a despised schoolboy.

1946

(con. 1912) B. Marshall George Brown’s Schooldays 102: A ruin’s a chap who’s a swot and a funk and who’s rotten at games.