noun Nautical.

the area between the water lines of a ship when fully loaded and when unloaded.
a distinctive band of paint covering this area.

Origin of boottopping

First recorded in 1760–70; boot1 + topping
Also called boot·top [boot-top] /ˈbutˌtɒp/. Unabridged Based on the Random House Unabridged Dictionary, © Random House, Inc. 2019