Green’s Dictionary of Slang

a small, thin and/or deformed person.

1825		Pierce Egan’s Life in London 11 Sept. 261/1: Gibbons recommended, from his greyhound condition, he should go into training for a ‘Natommy vivante,’ and go round the country as own brother to the living skeleton.
1847		Bell’s Life in Sydney 16 Oct. 1/2: The portly host is gone, wasted away to ‘natomy’.
1909		J. Ware Passing Eng. of the Victorian Era 180/2: Nattermy (Peoples’). Word for a thin human being. From anatomy.