A catamaran is a type of sailboat with two hulls that are parallel to each other and are joined by the deck.
A catamaran's distinguishing feature is its two-part structure. It has two hulls that are side by side, linked by a single deck. Catamaran is one of a few English words that come from Tamil, and it was originally a simple boat with two hulls made from tied tree trunks. Now it can be a much fancier sailboat such as a yacht.