A catamaran ( derived from Kannada word Kattumara ) is a type of multihulled boat or ship consisting of two hulls, or vakas, joined by some structure, the most basic being a frame, formed of akas. Catamarans can be sail- or engine-powered.

Catamarans are a relatively recent introduction to the design of boats for both leisure and sport sailing, although they have been used since before recorded history among the paravas, a fishing community in the southern coast of Tamil Nadu, India, and independently^{[citation needed]} in Oceania, where Polynesian catamarans and outrigger canoes allowed seafaring Polynesians to settle the world's most far-flung islands.

In recreational sailing, catamarans, and multihulls in general, had been met by a degree of skepticism from Western sailors accustomed to more "traditional" monohull designs, mainly because multihulls were based on, to them, completely alien and strange concepts, with balance based on geometry rather than weight distribution. However, the catamaran has arguably become the best design for fast ferries, because their speed, stability and large capacity are valuable.