A deckchair is a light folding chair with a long seat of cloth, often canvas, on a wooden or metal frame. You can sit up or lie back. The name comes from the chairs people put on the deck of a ship; in Britain they became the classic beach and park chair you rent for the afternoon. It is mainly British English. In the US people more often say lounge chair or beach chair. Informal, everyday, a little old-fashioned in a seaside-postcard way. There is also a well-known saying, “rearranging the deckchairs on the Titanic”, for busy little changes that do not help when something is already going badly wrong.