Wiktionary
n. (context nautical English) The inward curve of the topsides of some ship hulls.
Wikipedia
In naval architecture, the tumblehome is the narrowing of a ship's hull with greater distance above the water-line. Expressed more technically, it is present when the beam at the uppermost deck is less than the maximum beam of the vessel.
A small amount of tumblehome is normal in many designs in order to allow any small projections at deck level to clear wharves.
Usage examples of "tumblehome".
Above Sharpe now, water dripping from its lower rungs, was a tumblehome ladder leading to the maindeck.
She was high-hulled, solid-looking, with a plumb bow, some tumblehome amidships and a double-ender stern.
The Victory was higher than the Frenchman, and the two ships' tumblehomes meant that even when their hulls were touching, the rails were still thirty or more feet apart.
The Victory was higher than the Frenchman, and the two ships’ tumblehomes meant that even when their hulls were touching, the rails were still thirty or more feet apart.