1. Hull - the body or frame of a ship. The hull is a central concept in water vessels. The hull is essentially what keeps the water from entering the boat and acts as the walls and floor of the vessel. Hull construction is usually performed at a wharf, in a dry dock.
The very first hull is thought to consist of a hollowed out tree log and was a Stone Age invention--in effect the first canoe. Hull construction then proceeded to keeled hulls, including ballast and on to modern double steel hulls with waterproof sections.
In the very latest sailing ships, hulls are often made of layers of foam and plastic, forming composite hulls, with a minimum of weight. Variations on the single hull can be found with outriggers, and craft with more than one hull, called multihulls.
2. Hull - the outer covering of a fruit or vegetable, may also be called a husk.