A lateen (/ləˈtiːn/, from French latine 'Latin'), also known as a latin-rig, is a triangular sail set on a long yard mounted at an angle on the mast, and running in a fore-and-aft direction. The settee can be considered to be an associated type of the same overall category of sail.
The lateen originated in the Mediterranean as early as the 2nd century AD, during Roman times, and became common there by the 5th century. The wider introduction of lateen rig at this time coincided with a reduction in the use of the Mediterranean square rig of the classical era. Since the performance of these two rigs is broadly similar, it is suggested that the change from one to the other was on cost grounds, since lateen rigs used fewer components and had less cordage to be replaced when it wore out.