an unlikely to be fulfilled wish

A pipe dream is a fantastic hope that is generally regarded as being nearly impossible. The term derives from the visions or delusions induced from smoking an opium pipe 'pipe dream' etymology entry in the Oxford English Dictionary, which was popular in Britain and America during the late 19th century and early 20th century. Some sources claim the term derives from the mescaline pipe .

Pipe Dream (known as Pipe Mania in Europe) is a puzzle game released in 1989 by LucasFilm Games and originally developed for the Amiga in which the player must connect pipes on a grid to support a flow of water from one endpoint to another. This game was ported to several platforms such as the Atari ST, Acorn Archimedes, Acorn Electron, BBC micro, Commodore 64, Commodore 128, Game Boy, Macintosh, NES, as well as both DOS and Windows 3.1.

Pipe Dream is the twice-weekly campus newspaper at Binghamton University in New York State. It was originally named The Colonial News but this name was changed during protests against the Vietnam War.

Pipe Dream is an American musical by Rodgers and Hammerstein. Its conception is tied up with unrealized plans by other collaborators to make a stage musical based upon John Steinbeck's best-selling novel Cannery Row. Steinbeck, who was writing the libretto for that work, discontinued, and instead began creating the story of a sequel novel, Sweet Thursday.