Green’s Dictionary of Slang

a skeleton; a very thin person.

1738		Swift Polite Conversation 41: Why, my Lord, she was handsome in her Time; but, she can’t eat her Cake and have her Cake. I hear she grown a mere Otomy.
1785, 1788, 1796		Grose Classical Dict. of the Vulgar Tongue.
1811		Lex. Balatronicum.
1823		Egan Grose’s Classical Dict. of the Vulgar Tongue.
1834		(con. 1737–9) W.H. Ainsworth Rookwood (1857) 143: That dried up old ottomy, who ought to grin in a glass case.
1859, 1860		Hotten Dict. of Modern Sl. etc.
1873		Sl. Dict.
1895		C. Crowe Aus. Sl. Dict. 55: Ottomy, a skeleton; a thin man.