The
Latin designation for the so-called '
seas' on the surface of the
Moon before
modern telescopes showed the dark areas to be dry plains. Since 1959
spacecraft probes and landings (both
manned and un-manned) have provided much detailed
information but their origin is still perplexing to
scientists.
The singular is Mare (e.g. Mare Imbrium), but there is a marked tendency to delatinize this terminology (e.g. Sea of Tranquility, Sea of Fertility etc).