Sinus Medii (Moon)

"Bay of the center"

Sinus Medii is a small lunar mare. It takes its name from its location at the intersection 's equator and prime meridian; as seen from the Earth, this feature is located in the central part 's near side, and it is the point closest to the Earth. From this spot the Earth would always appear directly overhead, although the planet's position would vary slightly due to libration. (wikipedia entry)

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