Triangular sails, also known as lateens (7 letters) and jibs (4 letters), are a type of sail used in sailing vessels. They are characterized by their triangular shape and are typically attached to a long yardarm that is suspended from the mast. Lateens are used mainly in traditional boats such as dhows and feluccas, while jibs are used in modern sailing vessels. Both types of sails are designed to maximize the efficiency of the vessel by providing more power and stability in the wind.