Mare Fecunditatis (Moon)

"Sea of Fecundity"

Mare Fecunditatis is a lunar mare which is 840 km in diameter. The Fecunditatis basin formed in the Pre-Nectarian epoch, while the basin material surrounding the mare is of the Nectarian epoch. The mare material is of the Upper Imbrian epoch and is thin compared to Mare Crisium or Mare Tranquillitatis. This basin is overlapped with the Nectaris, Tranquillitatis, and Crisium basins. (wikipedia entry)

A mare is a "sea" or large circular plain. On the Moon they are named after latin terms describing weather and other abstract concepts.