noun. 
                    An oval yellow spot near the center of the retina of the human eye, histologically defined as having two or more layers of ganglion cells, responsible for detailed central vision.
                  
                
                  
                    noun. 
                    A spot, as on the skin, or on the surface of the sun or of some other luminous orb.
                  
                
                  
                    noun. 
                    A rather large spot or blotch of color.
                  
                
                  
                    noun. 
                    In planetary geology, an unusually dark area on the surface of a planet or moon.