great year: time required for one complete cycle of the precession of the equinoxes, about 25,800 years
entity: that which is perceived or known or inferred to have its own distinct existence (living or nonliving)
infectious mononucleosis: an acute disease characterized by fever and swollen lymph nodes and an abnormal increase of mononuclear leucocytes or monocytes in the bloodstream; not highly contagious; some believe it can be transmitted by kissing