the.com/multihull

means A boat built with two or more hulls (like a catamaran or trimaran) instead of the single hull of a conventional vessel, trading some stability-by-weight for speed and resistance to tipping.

from Straightforward 20th-century compound: 'multi-' (Latin multus, 'many') bolted onto 'hull,' the old word for a ship's body, itself traced back to Old English terms tangled up with both 'husk' (the hull as a shell around the ship) and 'hold' (the hull as what holds things). As catamarans and trimarans moved from Polynesian and Pacific sailing traditions into Western yacht design and racing through the 1900s, English needed a plain word to cover 'boats with more than one of these' — so it just said so.