noun Any representation (map projection) of part of a sphere on a plane surface.
noun A map constructed by stereographic projection, as described in Ptolemy's treatise Planisphaerium and later used in planispheric astrolabes
noun A map of the whole world, especially those from the 16th–17th century
noun Any of several charts of the celestial sphere having an overlay or window that may be adjusted to show the stars visible at a particular time, or from a particular place.