In architecture a pavilion (from French, "pavillon", from Latin "papilio") has two main meanings.

Pavilion may refer to a free-standing structure sited a short distance from a main residence, whose architecture makes it an object of pleasure. Large or small, there is usually a connection with relaxation and pleasure in its intended use. A pavilion built to take advantage of a view is referred to as a gazebo.

Such pavilions may be small garden outbuildings, similar to a summerhouse or a kiosk. These were particularly popular in the 18th century and can be equated to the Italian casina, usually rendered in English "casino". These often resembled small classical temples and follies. A poolhouse by a swimming pool may have sufficient character and charm to be called a pavilion. By contrast, a free-standing pavilion can also be a far larger building such as the Royal Pavilion at Brighton, which is in fact a large oriental style palace; however, like its smaller namesakes, the common factor is that it was built for pleasure and relaxation.