origin: 1565–75; Latin annulāris, equivalent to annul ( us ) ring (variant of ānulus ) + -āris -ar1
of, relating to, or forming a ring;
➝ ex: the annular diaphragm of a microscope.
In case you haven't seen tonight's "supermoon", this word was chosen to avail another opportunity to view a cosmic effect -- Annular Solar ‘Ring Of Fire’ Eclipse (May 20, 2012). If you do not fall into the direct path [map], a partial eclipse can still be visible. A warning though, some say Nostradamus predicted major earthquakes that day, which would also coincide with another ancient Mayan/Mesoamerican belief in the return of Quetzalcoatl! Oh yes, and protect your eyes.
image of supermoon unedited, except for watermark