Palus Somni (Moon)

"Marsh of Sleep"

Palus Somni is an area of level but somewhat uneven terrain that lies along the northeastern edge of Mare Tranquillitatis and the Sinus Concordiae. It has a higher albedo than the lunar mare to the west, and is a shade of grey typical of continental terrain. A few minor craters lie within its borders, with the flooded Lyell along the west edge, Crile to the east, and Franz to the northwest. (wikipedia entry)

A palus is a "Swamp"; small plain. On the Moon they are named after latin terms describing weather and other abstract concepts.