tumblehome

noun

1. The inward curve of the topsides of some ship hulls; the term was also used for rolling stock on railways in Britain.

   “The bodysides have a gentle tumblehome, which gives the machine impressive solidarity of appearance, well set off by the new B.R. standard livery of light-skirted green.”

   “Like the Pullmans, however, there would be a familiar curving tumblehome and cant rail, and a similar white window surround […].”